I didn't think to check this out at the time, but is the backrest for the passenger removable on the 600 touring, when not in use?  This will be my first Cfmoto machine that I will be picking up this weekend.

Yes it is, if look at the back of the back seat and you will see a handle. Lift up and pull back on the seat.

Only issue is it does expose the battery

Only issue is it does expose the battery

are there any covers to buy that would cover the battery while not using the back rest?

Only issue is it does expose the battery

are there any covers to buy that would cover the battery while not using the back rest?

Not that I'm aware of.