re: Talk to me about Receivers and surround sound

It all depends on what you want and what you're using it for. Everyone has different taste and what sounds good to me may sound like garbage to you.
Me personally, I listen to a lot of music and don't care about having surround sound. I don't watch many movies either, mostly sporting events. So I built my system around what I was going to use it for.

Those speakers you have will get the job done, but you'll be missing a lot of detail in the sound. I'd highly suggest looking for a better center channel and some towers for the front, but that's me. You may not care enough to justify the cost.
You could also look into some decent bookshelf speakers, some of those produce amazing sound. But that's only going to matter for music.

If you're just watching tv/movies with it, then the vast majority of your sound is going to come from the center channel. It's the single most important speaker in the entire setup, so get a good one.
Also, I don't know anything about that sub. You can always upgrade it later, but for the price you may want to look into a BIC sub. Excellent sound and quality for the price. If you're a baller, maybe a Velodyne.

I've recently been turned on to Monitor Audio, that's what I now have for my setup and they are absolutely amazing. They aren't cheap, but not overpriced either. There's some great deals to be had on their speakers if you check ebay. Find a local dealer and go listen to them, you'll be impressed. I replaced a set of lower end B&W speakers with them and don't regret it at all.