Basic Action Super Heroes!

I'm not clear on how many Perk Points you get with the "Membership" Advantage. I see that you can get additional point by taking Membership Disads, but I assume that you must get some number of them as a base. Or is that wrong?

The amount the Narrator says you can have. There is no hard number because sometimes you might want to be a 20-point character who is part of some REALLY powerful group like SHIELD (and that is perfectly reasonable that a SHIELD Agent could be 20 points) or you could have a 40 point character who is just part of the "Local superhero team" that doesn't have a whole lot of perk points.

So it is something that the Narrator and the Player should work out together.

Hmn, I see the reasoning. But, if it's hand-wavy like that, then why do you get extra Perk Points for taking a Disad? That doesn't quite fit to me.

If the Narrator says "You get 10 Perk points" you'd be able to get 12 by taking 2 Drawbacks or 10 with 0 Drawbacks, or 11 with 1 Drawback. You still have some control over the process; the Narrator is just the one setting what the boundaries are.