I have a variable number of addresses I want to send Btc to and I have a wallet (created in NBitcoin) as the source. A couple of questions.

All the examples use the fluent methodology to declare, create and build the transaction (using TransactionBuilder) all in one line. How do I call the .Send() a variable number of times? There doesn't seem to be an IEnumerable version of the method.

Secondly, from the wallet, how do i determine which of my txOuts I can spend? Do I just add everything (or just enough) and get the change back? What I mean is, how do i determine what is spendable?