Yeah its not pay2win, more like pay2getaheadfaster, you can get thru it as a free player easily but it just takes a while. And b slot medals are tradable, usually about 90-95mil on the board, read up on your character tho before buying it, if youll need it then buy it for sure, if not then id invest in something else unless you just want it. Also, reading forums will help you out so much in progressing and getting money.
Btw, yay got an endgame spear for ara, only cost 500mil