I've been looking into the possibility of putting some newer components on my (mostly) stock Trek 520 from '89. But i have some questions first!

1. Id like to move to 700c wheels, and I know they'll fit (personally tried it), but am I correct in assuming I need to find a wheelset that has a 7-speed cassette hub on it to move my own cassette over (bummer if so because i love my 105 hubs)? Anyone know of any decent wheels that fit the bill?

2. I also want to move to integrated shifters, and ive seen ONE set of Sora 7-speeds on ebay. Does anyone know if these will work?Amazon.com : Shimano ST-A070 Road Shifters 2 x 7-Speed Black Pair : Bike Shifters And Parts : Sports & Outdoors
I have changed the front chain rings to a 50/42 setup from stock, so I really like those for the price.

I'm keeping all the Stock parts in case I ever want to sell it, but this frame is so amazing I don't want to get rid of it! And, money is very tight for me (college). Thanks for your help!