1) DH and DS offer the opportunity to show popunders on your parked pages that also bring in money.
2) Search revenue is a DS term only that shows how much you made from users searching (And clicking, although it doesn't say it) from your landing page on DS.
3) Revenue Per Click (How much each click brings in)
4) Revenue Per Mil (1,000) (How much each 1,000 visitors would bring in assuming your current CTR and RPC stays constant.)
And the difference b/n RPC and PPC is which side of the equation you are on: For advertisers, it's PPC (Price Per Click) and for publishers it's RPC (Revenue Per Click).
..Mitt..