I asked this question, and then I figured out the answer with help from folks here in this exchange.
I have contract functions that return a uint256 amount. This amount is related to the contract's balance. So it shows up in Wei (I guess), as a very large number, in Ethereum Wallet.
Can I return this number in Ether so that it shows up in a more friendly way in the Wallet and I don't risk messing up units in calculations? Or do I have to manually convert units and return a uint256 as divided by some constant?
Well, a function returns a value of a given type, for example, in this case, uint256.
The money units available in solidity are constants, and have no relation to the type system.