Change is always returned to whichever address you have selected as your default at the time
That pretty much answers every question I had and resolves pretty much all of my issues as well. If you just keep an empty address as the default it appears you are good to go.
This is a great wallet. Thanks.
Not 100% correct.
Change always flows back the the address that contributed the most input. So if you have two unspent outputs on two different addresses and make a transaction that spends both outputs, then any change goes to the address that provided the most input.
So why is that?
If someone convinces you to import a private key that he also controls, then you will only send change back to it if it is the largest contributor. This way you never risk someone giving you a private key with 0.0001 and you send change back to it > 0.0001.
For cold storage spending (the trivial case where there is only one address in play) it means that it always goes back to the cold storage address.
Once we get to HD wallets we will have
1. Spending from HD wallet - change always flows to a new address
2. Spending from cold storage - change always flow back to your paper wallet
3. Spending from 'classic' addresses (the ones we have now)- change always flows back to the address that provided the most input.
(2 and 3 follow the same rules actually)