If you create a new wallet.dat, encrypt it, back it up, getnewaddress and send funds to it, does the back up of the wallet.dat also have the new address? Does getnewaddress actually create a new address or just assign one? Is that what the keypool size is?
If you generated new address in a wallet, the backup of the wallet will not contain the new address unless it was backed up after the new address was generated.
That is not my understanding. getnewaddress rpc command will get an address from the keypool first, unless it ran out; and add it to the addressbook as a 'receive' purpose address book entry. So the backup wallet.dat would have the new address.