Suppose a node begins broadcasting a signed transaction.
Question 1. At what stage is the signature verified? In §5 of the whitepaper, verification only appears during block acceptance after mining. Isn't it more sensible for a node to verify the signature on any transaction it tentatively places in a block?
Question 2. For how long does a node broadcast a transaction? How does it know when to stop broadcasting a transaction, either because it was accepted, or because it is invalid?