I have downloaded the bitcoin client and the client has synced with the network.  I have made a few transactions with my wallet, both inbound and outbound.  I have also encrypted my wallet with a password. I have also backed up my wallet, locally, and also emailed it to my gmail account.  Two questions...

1. will the wallet address that I have used in the past continue to be mine forever? Or will it change after X number of transactions?

2. If I backed up my wallet 2 months ago, then made several more transactions after the backup, then my PC crashed, then restored from a 2 month old backup, would my restored wallet be 100% exactly the same as the one that crashed? Would I have the transactions that occurred after the backup?