1) Are you talking about the RPC password(in the .conf file?) or wallet encryption(in the menu of the client)?
After I encrypted my wallet it did ask me every time. though now I use bitcoind without the GUI (graphical user interface) so i am not sure about this.

2) you can just backup the wallet.dat file. why does it matter how the data is stored inside?
the wallet.dat has ~100 new addresses - each time you send money a new address is used, so you should create a new backup once in a while (~each 50 transactions should be safe)
there are security risks with import that have nothing to do with encryption - there is a thread in the dev forum about this.