ONT/SNA to FWA

I'm trying to plan a trip to FWA this month. I live closest to ONT
but I'd also consider leaving from SNA. I'm trying to get a cheap
ticket AND arrive on the same day I leave and arrive by mid-evening. So
I have a couple of questions.

1. Am I really going to get a lower price by using something like
Expedia or Orbitz as opposed to going directly to an airline? What's
the best way to get a cheap ticket? It's cheaper from LAX but I don't
want to have to get to LAX early in the morning.

2. Will I save money if I ask the airline for a route that is different
than those they offer when I do a search? For example, Orbitz has me
going to Atlanta to get to FWA. That's a long trip in coach and not
very direct. I'm puzzled why, if I choose ONT as a starting point, I
can't get UAL to show a route that goes to, say, DEN to ORD to FWA,
instead of really odd connections. Why aren't eh routes more
straightforward? I know about hub cities and therefore I'm not
surprised that AA wants to go through DFW, but why would UAL not go more
directly?

Thanks.