I don't live in Seattle anymore, but pre-welcome to Seattle!
For food -
I recommend Uneeda Burger or 8oz. burger for, well, burgers (Uneeda has got a pretty decent rotation of beers, can't remember what they served though...).
Paseo's has got some really great Caribbean sandwiches.
Afterwards you can hit up Molly Moons for a decent scoop of ice cream.
For things to do -
Pike Place Market is a must. It's right across the venue and there's a lot to see. Mostly just food, but if you wander inside there are a couple shops that sell random knick knacks.
Definitely check out the gumwall. It's kind of disgusting, but cool to see. (The smells you'll discover)
There are a few places you can check out for food too. My personal favs are Pike Place Chowder, the gyro stand, and the Crumpet Shop (if you're into overpriced British breakfast goods)
Also, I'd highly recommend checking out Chukar inside the Pike Place Market. They have AMAZING chocolate covered cherries and phenomenal chocolate covered pecans. Good for souvenirs.
The Seattle Art Museum is nearby the Pike Place Market too
Westlake Center is worth a visit if you're looking for some good old commercial shopping
The EMP is pretty cool (Excuse me, the Museum of Pop Culture). As its name implies, they showcase a lot of modern pop culture related things like props from shows, history of bands from Washington state like Jimi Hendrix and Nirvana, that kind of thing.