Answer to your first question. Generally 1 confirmation is not a guarantee of a confirmed transaction there are a few reverse miners which can reverse the transactions on the network. However, the rule is that more are the number of confirmations on the transaction the lesser is the chance to reverse it. Almost after 3 confirmations the chances become negligible. Then it comes to tracing ip address. Tracing any ip address related to a private key wallet is certainly impossible so no way to trace the person associated in crime.
Wait what? Miners can't reverse transactions. Bitcoin transactions are uncensorable, meaning no one can voluntarily stop them nor reverse them. There is only one way to "stop" a transaction from happening, and that's by respending an (unconfirmed) input with a higher fee,
praying that the latter transaction will get confirmed first -- also known as double spending.
Bitcoin transactions are traceable through the blockchain, yes, but there are ways to cover your tracks.