1. It was NOT personally clear to me that Chinatsu was going to be top (usually these things are obvious, occasionally we get a surprise). I don't think it was the reason for Ari's transfer though; it's impossible to know for sure, but my guess is more because of Oda (they don't want her to wait for Ari to finish) and some need to balance Hoshi. With Chinatsu as an older top, she can stay for a shorter time (similar examples would be Sou Kazuho and Hokusho Kairi, also older tops who stayed for three Grand Theater shows) and Oda can become top sooner.
2. I had a feeling Coto would be a long top for a number of reasons... 1) she's extremely popular and puts a lot of butts in seats, 2) she has a reputation for being a "mini Yuzuki Reon," who also stayed for a really long time, 3) the Hoshigumi producer has a bit of a reputation for putting a lot of stock in high-powered top stars and somewhat neglecting the nurturing of his track, and 4) until Ari came over there was no clear successor, which made me think they were going to ride Coto until they figured it out.
3. I've only heard rumors about this... one that Miya Rurika didn't want to be top star, one that Manaki Reika was so popular they designed the troupe around her and the producers didn't like her and Miya/Kacha together as much as they liked her and Tamaki together... but again, there is no way to know for sure.
4. Firstly, LGBT+ culture is NOT practically nonexistent in Japan—not saying this to correct you, but it's an impression a lot of people get and it makes them sad! So I want to share the reality of it! LGBT+ activism is way less prevalent than in other cultures (and as a result, legal protections are definitely behind), but this is true of pretty much all types of activism (I had an interesting conversation about this with a group of Japanese climate activists). There is a rich LGBT+ nightlife scene, and over the years Japan has been fairly ahead of the curve when it comes to queerness in media and fan culture. There is, however, a very "we pretend we do not see it" energy despite the prevalence. That said, Takarazuka actresses are almost definitely forbidden from talking about this while active, and discouraged while retired (especially if they stay in entertainment). Even if they are not actively discouraged, because there is no culture around being open about it on a real and personal level, they certainly wouldn't out other people and likely wouldn't out themselves. There are OGs both in and out of entertainment who are not shy about living as their honest selves and you can pretty much tell, but it still doesn't tend to be something they openly talk about (Nanami Hiroki and Miya Rurika have discussed breaking gender norms in interviews, but have skirted around saying anything definitive about themselves). The one exception I can immediately think of is Misuzu Aki retired and blogged about moving to Europe with her female partner.

• Ok for one, queen of musumeyaku Hanafusa Mari. She had five husbands, and was top for 8 1/2 years (she is hella old old old old money but still). No one is ever going to do that again.
• Hatsukaze Jun, the musumeyaku of the BeruBara Boom.
• After that, there are a lot of musumeyaku who went on to successful careers in TV and movies. Decades ago, there was actually a very intentional Takarazuka-to-silver-screen pipeline. Off the top of my head, Yachigusa Kaoru was one of those, but there were so so many and I'm doing this while slacking off a Zoom meeting so I can't look them up right now lol.
• More modern examples of the above: Kuroki Hitomi, Dan Rei, Konno Mahiru, Emi Kurara, Haida Shoko, among others...
• Even more recent, Sakihi Miyu, Manaki Reika, and Maaya Kiho have been killing it with lead stage roles since retirement, something that in the past only former top otokoyaku were able to achieve with any kind of consistency.

• The first generation of top otokoyaku: Anna Jun (Flower), Haruna Yuri (Moon), Migiwa Natsuko (Snow), and Ootori Ran (Star). These were the prime participants in the "Berubara Boom," skyrocketing Takarazuka's mainstream popularity, and leading to the establishment of an official top star system.
• Ooura Mizuki, considered one of the best dancers in Takarazuka history, went on to become an internationally renowned tango dancer. It's impossible to attribute this definitively to one person, but I also think she started a steady incline in the difficulty of Takarazuka choreography over the years.
• Amami Yuuki, who you mentioned, was famed for her natural acting style, unusual for the stage at the time. She became the youngest top star ever largely due to her popularity, and the fear that she would be offered better opportunities on and off stage outside of Takarazuka. She has also had a successful career in movies and dramas, and is probably the biggest household name amongst OGs.
• In my admittedly biased opinion, I think Mori Keaki and Ichiro Maki set the standard for top stars and nihonmono
• Maya Miki was noted for actively studying everyday men and somewhat revolutionizing otokoyaku style (think charmingly disheveled suit vs. the traditional buttoned up tailcoat look). She has also had a successful TV/movie career post-Takarazuka and is a household name in Japan.
• Wao Youka is the longest running top otokoyaku, and had extremely notable chemistry with Hanafusa Mari (whose record of 8.5 years and 5 husbands will likely never be unseated)
• Yuzuki Reon was 2 months shy of Wao's record, similarly had notable chemistry with Yumesaki Nene, and was wildly popular. She and Maya Miki are the only two otokoyaku to perform in Nippon Budokan, which is 7x the typical Takarazuka venue seating capacity.
• I also have to mention Nanami Hiroki for a different reason. While those above were IMO very influential otokoyaku in Takarazuka, Nanami Hiroki's graduation marked a notable turning point in the opportunities available in the entertainment industry to OGs who didn't make top. Prior to her graduation, it was fairly rare even for a top musumeyaku to get regular leading roles post-Takarazuka, never mind actresses who were not top stars. Nowadays we see a lot more of this. Miya Rurika has gone on record in print saying the breadth and success of Kai's OG activities have hugely influenced her and paved the way to "be herself" in her career, and we've seen a large number of 2 and 3-ranked former otokoyaku follow similar steps since.

• Star troupe RRR/Violetopia: Takarazuka performances from 1/1-1/5 (opening day becomes 1/5 at 3:30pm); The 3:30pm shows on 1/11, 1/18, and 1/30 (2-show days become 1-show days); Shinjin Kouen is canceled. Tokyo performances at 6pm on 2/29, 3/5, 3/18, and 3/28; at 1:30pm on 3/12 (2-show days become 1-show days).
• Flower Troupe Arc-en-Ciel: Takarazuka performances 2/9-2/10 (opening day becomes 2/10 at 3:30pm); 2/18 11am, 2/20 3:30pm, 3/5 3:30pm; Shinjin Koen. Tokyo performances 4/13, 4/14 (goes from two shows to one, 1:30pm becomes opening day); 6pm shows on 4/18, 5/2, 5/7, 5/14; 1:30pm shows on 4/25 and 5/24.
• Snow Troupe Boiled Doyle on the Toil Trail/Frozen Holiday: Tokyo performances at 6pm on 1/9, 1/16, 1/23, 1/30; the 1:30pm performance on 2/6.

• The 110th anniversary ceremony scheduled for July
• The 2024 Takarazuka Special
• Sports Day

Regarding the sudden death of a Takarazuka actress of Cosmos Troupe, we continue to extend our sincerest condolences to all of her surviving relatives. As announced on December 7 in relation to this incident, based upon written notice received from the family’s legal team on 12/6, along with the contents of the press conference held by said legal team, we made the decision to conduct a second investigation that will examine the facts of the case more closely. We are still taking the problems outlined in the investigation report that we released on 11/14 very seriously. However, as the issues present are not limited to those outlined in said report, after taking into account the information shared by the family’s legal team via the aforementioned documentation and press conference, and with the deepest consideration for the bereaved family’s thoughts and feelings, out of sincere desire to continue our earnest consultation with the family, we have made the decision to rescind publication of our report at their request. Additionally, we will continue to work toward achieving a formal compensation agreement with the family.

In the aftermath of the sudden death of an actress from the Takarazuka Revue in Takarazuka City, Hyogo Prefecture, we've learned today, December 19, from an inside source, that the company has received numerous messages with threatening contents via post and email, demanding that the reopening of performances be suspended.