Eighteen to master. That's the size of the launch cast of the game.
I am awful at stance changes mid-combo (at least those requiring circular motions; I've messed with Aki and had an easier time with hers), so I committed to relying on Chun's regular and command buttons. Combined with her high walk speed and fast/generous hitboxy/mostly cancellable buttons, I could usually walk people down. I fished with 2MK and 2HK the most although I threw out 5LP, 4/6MP, or 5HP in neutral too.
2MKs I typically buffered into MK Lightning Legs. Not long after starting Chun, I learned LK and MK Lightning Legs are a massive -8 on block and very punishable at virtually all ranges. The HK version is safe at -3 and I did catch sometimes in a frame trap, but, as I learned, most people don't know about how punishable the lighter versions of LLs are, so usually I just let MK ride. Also, while the heavy knocks down, medium legs on counter hit hit allows at least another light (or medium on punish counter) to combo. Tip for people fighting against Chun, her voiceline for HK Lightning Legs is much higher pitched than the other ones, so if you don't hear that and the animation seemed fast, go ham on punishing her.
At close range I sometimes mixed in the 3HK flip - Usually didn't work in simple neutral but when my opponent was attempting to do something at the same thing they usually got caught in the crossup and I could combo into 2LP, 2LP, HP Kikoken or MK Lightning Legs or something. Hazanshu at close-mid is something I started mixing in a little by the end but it felt so dangerous to use. Never quite the got hang of it.
Being on the other end of throwing out a HP Kikoken from mid/full-screen and watching it dissipate in front of an opponent's face as they waste bar trying to parry nothing is very satisfying. If you're fighting Chun, unfortunately the voiceline's the same for all her fireballs so you've just gotta rely on the visual cueue to determine which she's throwing (and MP also dissipates from full-screen and is still pretty slow so you have to know the speeds for all of them).
On knockdown, the drive rush button I went to is 5MP. It's a very Sagat-like 5MP in how it's plus and stubby (just not as plus as Sagat's). I tended toward 4HP to combo but in retrospect 2MP or 2MK would be better because 4HP really only works very close-up. Hell, 2MP naturally links and would let me cancel into OD Spinning Bird Kick but oh well.
AA I used was exclusively Tensho Kicks. Good move, although even with the simple 22K input I was often not fast enough to pull it out in time and shied away.
Cash-out combos vary depending on point in the match, but on jump-in, jump-in HP, 2HP xx OD Spinning Bird Kick, HK Tensho Kicks does over a third of most characters' life bar on counter hit (3340). The supers can be substituted for tensho kicks although my use tended to be clumsier. Medium xx MK LLs xx Level 3 or OD LLs xx Level 2, jump 2MK, 2MK, 2MK/LLs. Once on my climb I pulled off a cool overhead combo: DR 3HP, 2MP xx DR 5MP, 4HP xx HK LLs xx Level 3.