Yes at the end of last season is better to sell them, and stars are just some visual statistics.

And last part is not true, I won CL and League at level 6 or 7 with 15-20 tokens and at the end of season I have saved 16 tokens or something like that.

Is true that you need to be a bit lucky, dosent metter level if you will find somebody who will spend a lot of moneys you can be in problem.