And for some reason I prefer her default gothic-lolita-anime-cosplay uniform 
You don't really have to spend money. It just speeds up the process. Only thing that you have no choice but to pay for is Carnage. There are some players who spend alot on this game, and others that don't. Both can still get to 'end-game' content, just the paying players get there faster. That's one thing good about this game.

If there's any advice I can give, is that:
1. Focus first on no more than 3 characters to get to level 60. Level their gears and ISO-8 (a good start is gear level 10, and at least 3 star ISO-8s). I suggest choosing some of the better, farmable characters (from story and special missions) for that (there are guides around that list the good ones).
2. Use these characters and try to complete the entire story mission campaign. Aim for 3 stars on each level. When you're stuck on one, farm the mission below it for exp and level up. Try the next mission again. Rinse and repeat until you've completed all story missions with 3 stars each.
3. By the time you've done number 2, your 3 characters should be level 60 already. At this point you should be able to auto play almost any story/special mission to farm other characters. This part will be a long, constant process, unless you choose to spend money. If you're pressed for time and have enough clear tickets, you can use them to instantly clear a story mission for a character's biometrics (though this doesn't give you any exp).

It's a long haul game, but you don't have to play a few hours a day. I suggest logging in everyday and aim to complete all the daily trophy achievements. If you can afford to do more than that (i.e. all Villain Siege stages, Alliance Battle, Co-op, Battleworld), even better. Doing that will help you upgrade your existing characters in every way. After that, it gets easier. You'll eventually get there la. 

depending which uniform you're after. team ironman and antman civil war uniform are not on sale this round
this game is a year old, there are still loads of people who are playing since launch.
playing hard is a very subjective thing. if you don't mind me asking. if you're in an alliance. what's your daily average points?

like sifu Spade7 mentioned, there are those who paid alot and those who paid a little for those monthly subscriptions crystal/bios and still reached the same goal in the end, just the matter of how fast.
maybe you could give us an input on who you're working on right now, so we could have a slight idea of the direction you're heading to.

emulator within an emulator? 

emulaception

btw, i heard you need GUK

need donation?

  good master hitz

i'll whatsapp you in private later on the procedure. you manage to run and link up your account already?

yup! try again and do inform how it goes 

our alliance have whatsapp.. very active also. interested to join?