How are unconfirmed balances processed?

self.Bitcoin1m ago
I recently did some transactions: Wallet A -> Wallet B -> Wallet C. The first transaction did not clear for a long time - maybe 1hr or so. It was 2sat/byte. I'm pretty sure Wallet B had ''receiving X BTC'' fairly soon - 0 confirmations ofc. Then I made the 2nd transaction at this point. 1. Is it possible for both these transactions to go in the same block? Or must the 2nd transaction go in the subsequent block? 2. Is it possible to transmit those 2 transactions to the network with 0 confirmations or did I just imagine that? 3. If it is possible to queue up transactions like this, for the same funds, is there a way to 'rescind' a transaction before it enters a block? Causing a failure of these unconfirmed transactions?