Breakin should be performed per the instructions.

You don't need a pump unless the fuel tank is going to be far away from the engine. Muffler pressure is usually enough, unless your muffler doesn't provide enough pressure. Many after-market mufflers do not provide enough pressure, and you may have to restrict the exhaust outlet on those mufflers to generate good pressure to the tank.

Oversize fuel tubing and a clunk with a larger I.D. will not hurt fuel draw. Large engines draw a lot of fuel, and fuel-line drag can become a factor.