To all the religious players out there, can you guys help me 
1) What's the purpose of my leader card? I know it's there to be my display pic but does it hav any other purpose? for instance will my leader card be the one fighting the bosses so its best that I have a strong leader?
2) Say you're fighting a boss. What determines if you'll win against it? is it the strength of your leader card, your stamina, etc.?
3) How should you go about enhancing cards? does it make a difference if i use strong, rare cards as enhancers or normal cards with low stats? also, if im using normal cards with low stats as enhancers, is it advisable to evolve them fully beforehand or will i get the same results if i use them as enhancers individually without evolving them max?
thanx!!

1) What's the purpose of my leader card? I know it's there to be my display pic but does it hav any other purpose? for instance will my leader card be the one fighting the bosses so its best that I have a strong leader?
2) Say you're fighting a boss. What determines if you'll win against it? is it the strength of your leader card, your stamina, etc.?
3) How should you go about enhancing cards? does it make a difference if i use strong, rare cards as enhancers or normal cards with low stats? also, if im using normal cards with low stats as enhancers, is it advisable to evolve them fully beforehand or will i get the same results if i use them as enhancers individually without evolving them max?
thanx!!