I am working with a contract that has multiple 'contract' statements. Why does Remix deploy one at a time, and how do several contracts get deployed with multiple?

should additional contracts be converted to functions?

You can either put the code in one contract, use "contract A {}" and then "contract B is A {}" or deploy contracts separately and point from another contract to them.

"contract B is A{}" ........ do you have to import A first?

Yes sure, you have to have A and B in one file then or import the other file.

Makes sense, thank you.

You're welcome :)