Information about incoming transactions for a number of addresses
I'm not an expert here, but it looks like you're on the right track. See:


Bitcoin API (JSON RPC)
API Calls List


I'm guessing you can use the JSON RPC format to make the calls you need (i.e. "getbalance" and "getaccount" calls). 

As for reading the sender's address, perhaps "listtransactions" helps?