Literally we got in game purchase yesterday, my suggestion here its to play this miscrits like a new game, literally a new game, and when u feel u need some platinums or gems for a specific crit for pvp then u can expend ur money without worries

It depends really you can increase a random stat by 1 every level but it is only worth in my opinion on s+ miscrits which are hard to find, or some not s+ meta pvp miscrits.

I would recommend personally to save all platinum you get to buy some of the better rank perks.
Then do your daily missions they removed pvp wins from daily missions yesterday.

Interact with the well in town for a free reward once per day

Do you free Daily Spin

Give the miscrit collector the one random b+ or lower rank miscrit for play each day

Once you hit player rank thresholds you get 1 free option and can buy the other.
personally i ignore the increase xp gain. and save for the rank 200 and 300 other perks which are nice the 150 rank one is good too i would get the 150 rank one after rank 200 and 300 ones those i would say are worth saving plat for

It is generous enough i think although you can get plat and stuff from arena wins but i dont like pvp and only do it for the rewards.

You Gain player rank by capturing and evolving each unique miscrit once so you get 4 rank per 1 miscrit that you fully evolve.

I was thinking about this earlier, specifically how long it would take as F2P to train up a "competitive" crit if I were to min-max it as much as possible. The quick math I did in my head was somewhere around less than 500 Plats per Crit; 34 Plats per bonus points when you level, then you probably want to re-bonus it which is around 150-167 Plats and then full Relics which is probably around 240~ Plats. You probably earn a little less 300 Plats per month, I did really keep track on how much Plats from Dailies you get seems to vary between 10-12. I didn't account for one time rewards you get from Achievements/Campaign or Daily Spins/Wishing Well.

Can someone correct me if I wrong?

technically if you had the wishing well perk you would get double platinum, side note what does rebonus do i've seen the option but have been saving my plat recently.

You might not know this but this game is a facebook game port from like 2010-11, they had premium currency and pay-2-skip before mobile games. Still, they were very much playable as a f2p although they sometimes made it very tedious to do so with long waits and some of the better units locked behind premium currency that you'd get very slowly without paying for it. This one isn't really pay-2-progress since you can beat it with normal, non-premium boosted miscrits, it's only really useful for min maxing a pvp team but if that's what you're after i wouldn't bother playing.