I can't answer all your questions, as I'm UK based and have little experience of the US training system. I'm sure others will help with where to go.
As for a degree, I believe that all the US majors require their pilots to have a four-year degree qualification, so you're going to have to get one!
23 or 24 is a quite normal age to be entering the profession; some do it earlier, some much later.
The maximum earnings in the US majors is in excess of $300,000 pa for a senior training captain on B747/777s. However, earnings on regional airlines can be below $20,000, and it takes a good long while to get up to the seriously-well-paid positions! You have age on your side, so I wish you luck.