would like to know if there's anyway of knowing how many games i have left of toxicity before the two weeks ban.
Technically: One game. You are not supposed to be toxic AT ALL, not just rarely. You have been warned about your behavior and if you don't stop being toxic, Riot will use harsher punishments. You might get lucky and play more than 1 toxic game before you get punished again, but technically (and often practically) it just requires one more toxic game.
Also, do you still get ranked rewards if you get a 2weeks ban and do all toxic punishments reset when a new season starts?
Riot hasn't announced this for this year, but if it works like last year you won't receive season rewards if you have been banned in the last 3 months of the season. Toxicity punishments do not reset with the new season they only "reset" dynamically by you not being toxic for a long time.
So like i would get 10games chat restriction again instead of two weeks ban if I get reported by kids?
No. The next step for you is the 2 week ban. And you won't get a punishment for random reports, reports are always checked. You will only get a punishment if you are actually toxic.