Should be around RM220 or RM230+6% (if any) for Platinum. I'm also a Plat member; but with AIA Vitality received 30% rebate for monthly membership... so every month I'm only paying RM170 or so. You can refer to one of my AIA Vitality post in this thread - probably 1-2 pages back.
Platinum price is as per above. Not sure about single club. I'll recommend to go for Platinum for easy access to all clubs. Also refer to my AIA Vitality post 1-2 pages back - you can save a lot with this, no joke. I'm surprised to hear people still paying full membership fee when they can benefit from Vitality.

Also, FF prices are pretty much fixed. Not sure from whom you heard can nego, but sadly, it's all fixed. The nego part is likely to be waiver of registration fees, admin fees etc that you pay when enrolling in the membership. Ask for the free gifts as well (bag/ tumbler etc).

Yes, it's only for AIA insurance policy holder. I've heard from some members that you can sign up with AIA Medical Card. However it's better to check with an AIA agent and see if this is truly eligible (lets not rely on hearsay): https://www.aiavitality.com.my/vmp-my/how_to_join

It's not RM12x ya, it's around RM170 after the 25% membership rebate (monthly). This is fixed, and no changes at the moment. I've signed up for Vitality for >1 year and still paying RM170+. If you're hardworking enough to hit the x number of gym sessions (ughhh 30 or 36? sessions) each quarter, you're eligible for 30% cashback of your membership. This amount will be refunded/ transferred directly to your bank account