how to get private key of address?
The validateaddress command will give you some information about a CredaCash destination. If the destination belongs to your wallet, then valudateaddress will give you the "hdmasterkeyid", which is the hash of the master secret used to create the destination. The information needed to spend billets sent to that destination is contained in your wallet's CCWallet.ccw file and could be extracted using the sqlite3 tool. What would you do with that information once you had it?
Thought about to back up private keys of storage addresses, good old practice of mine (and hopefully lot of others)
Easier to store 10 private keys than holding 10x 100 MB wallets.
Hope that will be an option once GUI wallet is available.