I've been playing this game for a long time now, I've reached level 44 after clearing all the stages then I replayed stages to get to level 45 but at only 14 experience points per stage it took forever. I was wondering if there's any other way to get experience, I see people up to level 50 or higher. Hoe did they get there?

So there's no other way to get experience?
Also I was wondering how come some +++ Cards can't be evolved even though it says that it can be made into a rare card

I've been playing for a while now but I have several questions, I'll post.a couple at a time then wait for response.
I was wondering if there's any other forums or websites where I can interact with players and fans of SS.

There's several +++ cards that can't be evolved any further, is it best to just sell these when I first get them?
I think it's a waste.of gold to evolve them any further.[[SIZE=7][COLOR=green][FONT=Arial]

I'm level 51, my 30.friends are levels 50-60 but when I can replace 1 party member with their leader on the Boss Stage all of their HP and attack points are lower than my lowest members points. Is this because they don't put their best card as their leader, is this a good strategy? If so why?

Press the "Social" tab on the bottom
then press the "Invite" tab up top
Then Press the "Friend Request " tab to see all the people that accepted your request
Then "Accept"