Questions on: validation

1, 2 and 3. Transactions that arrive through inventory announcements on the network are validated completely by checking the form of the transaction for sanity, executing the script, checking signatures, ensuring that the outputs they are spending ac
At Pruning the branches in Merkle Tree Nick ODell writes "A leaf (transaction) can be pruned when all of its outputs have been spent. " So I was thinking that if a transaction is one of the last few in a block, a miner can copy the transaction into t
From BIP66: The new rules are in effect for every block (at height H) with nVersion = 3 and at least 750 out of 1000 blocks preceding it (with heights H-1000. . H-1) also have nVersion = 3