*WARNING: THIS IS A WALL OF TEXT.
After that giant intro, finally here are my questions:
1) I am aware that while everyone is balanced, there is still the issue of skillcap, utility, and matchups with picking characters. I'd like a bit more information on the characters I have picked, and what I should be careful about using them as a new player. This will help me either revise my team, or adjust my style a little bit.
You can rush down with almost any character of the game, I think for a begginer you should first adjust your playset depending on simply what you like the most, so you can spend time both learning the game and enjoying it with those characters you like the most.
About those that you already started picking,
Mai
Use pokes, standing B then low D, walk and do standing A when close, Standing C as an anti-air (so far the best she has), low B, A, + something and do not abuse Kachousens, try not to use them unless opponent is being zoned by your st A pokes, knocked down, or after standing CD if it hits, really, otherwise you will end up getting bad habits and become fish bait in which you will be the fish, Mai is great in the corner, so focus on cornering the opponent through knock downs , mostly hop CD. She is better 2nd or 3rd.
Ex Kyo,
Too balanced to tell you how to better use it, he goes better first as he does not need Drive cancels to put good pressure upon any other character or inflict good damage with almost any hit confirm, multiple jump Down Cs from middle distance until you learn the cross up set up along with low or standing Bs plus qcf As will be your standard offense, save your metter for EX qcb D, those are life savers.
Shen
Shen is a no brainer overpowered character, just trust your standing C which has auto guard properties and when close its hitbox extends for some strange reason so he ends up punishing easily things that you will have a hard time punishing with other characters, focus on learning his combos first, those are easy as hell, then abuse jump CD from middle distance and jump D both short hops and high jumps when close to mix up and land your extremely easy and abusive life taking easy combos. The advanced game with him will come after that (grab mix ups, qcf C cancels and CD feints).
Leona
One of the hardest characters to learn, you started wrong with her but if you like it, forget about long combos and focus on low Bs pressure and mix that with run then grab, down+up C,A, back forward A, control SPACING, and earrings bait, I think her Ex back, forward AC or BD have frame advantage, not sure though.
Kula
Here is some true potential for a begginer, she is like mai, a poke character but she does land GOOD damage out of almost any hit confirm you can manage to learn and react to, down Bs plus standing B then something is going to be your base to put pressure, trust walking then st B, when close standing A then ACD, ACD, then B, avoid being rush down by using DP everytime you can force them to jump so they stay in the ground eating your pokes, go to training mode and practice all her hit confirms after st B with CPU or random guard, if you need any combo hints hit me up online on steam so I can show you. And Yes, she is really cool. Literally XD.