hi im lvl 2 and still need to figure some things out...

what exactly is gain? (gain percentage) and what does it do?

how do you increase stars?
ive been reading you need 25 quality to gain a star is that true?
if so how do you improve quality? i figure skill points distribution
comes into play here (attack defence physical)

for example if i have a player attack average is 20 defence average is 20 and lets say physical is 20
how far is that player from gaining an improvement in quality or gaining a star?

any correct explanation would be appreciated
thanks!