Finally staked some coins. Yay!
When I look in send->coincontrol, I don't see my stakes listed there.
So where do I look to see them?
You can find your stakes in the Transactions tab. Stake transactions are marked as
minted type.
How do I tell which blocks they originated from?
Hover over one of this transactions, and you'll see an additional info. The field you are looking for is Original UTXO. It will give you the size of the original block.