There is nothing you can do about the rust that is on your crank.
I would leave it and run the engine as is.
You can check the bearings by turning the engine over by hand (slowly) and feel for
any grinding or harshness as you rotate the crankshaft. If it turns smoothly, then
most likely your bearings are okay. If not then the bearings need to be replaced.

Remember to run your engine with fuel that has some castor oil in it, as this ensures that
the bearings and crank will get a proper COATING of oil.
Also run the engine dry of fuel at the end of they flying day, and adequately lubricate the engine with after-run oil.

Ryan