The Abramoff scandal was mostly a device to help the Democrats win an election. Lobbying did not begin with him, and it's silly to think it would end without him. Now that the power base is Democratic, and hence most of the recipients of the lobbying goodies are probably Democratic, nobody cares about the lobbying any more.

It would be hard to analyze these donations in detail. They cover not just candidates, but propositions, special elections, or anything up for a vote. I think that all else being equal it's fair to say that success would tend to track money spent, although I've seen some notable exceptions.