NLSNG bankroll and winrate

[bobdogbobdog]

I know this has been addressed countless number of times, but i feel different people have different opinions on the "optimum" number for these 2 issues. Firstly, what kinda bankroll should u have for each level in terms of buy-ins, considering that you definitely ARE a winning player (winrate 60% & above). Secondly, how many games do u need to have before u can correctly ascertain if you are above mentioned winning player. Is there any maths to go along with the number of games? Just curious. Thanks guys