Is there a method to import an existing Bitcoin address (using the private key) into a wallet managed by the API? If so, will blockchain.info recover the addresses value from previous blocks (thereby increasing the value of the wallet)?
The API and web interface work with the same wallets so if you import a private key using [Import / Export] in the javascript interface it will be available in the API as well. If you would like to import a key programatically you can use the importprivkey method from
http://blockchain.info/api/json_rpc_api