Don't worry about the tank, use it as is. I even use a piece of brass tubing in the middle of my clunk line to PREVENT it from bending forward (where they have a habit of getting stuck).

Flaps are certainly not needed, but if you have the servo and channel, leave them there for later on.

And yes, that 61 is extreme overkill for the plane. You could probably add at least an extra 10 pounds to the plane, and it would still fly quite well.

Welcome, and good luck!
Dennis-