Welcome to FT!

After flying US, UA will definitely be a step up.

Re status, I believe UA will match status one time.

Re your other questions, they're a bit vague to answer. About UA's service, it can't be any worse than US's. Price's are relative and depend on where you're going and how far in advance you buy. Flights out of DCA tend to be more expensive that flights out of IAD. Of course, you cannot fly nonstop internationally out of DCA (OK, Canada). And remember, UA has E+!

My suggestion is to start monitoring the UA Forum and read, read, read, the stickies.

Finally, most of us would walk before we'd fly WN.