Newbie audio questions

[ts0323]

I wouldn't exactly consider myself a noob to the video aspect of a home theater, but I don't know a whole lot about the audio part.
Right now I have some cheap Logitech S220 speakers that I bought for $30.
They aren't great, but they're a heck of a lot better than the TV's built-in speakers, and at least they have a sub.

Eventually I'd like to upgrade to some better speakers when I get enough money. However, I have a few questions about the whole setup ---
1. I understand I need an audio receiver + speakers. Do most speakers connect directly to the receiver and that's where they're powered from?
2. Would I connect my Blu-ray player HDMI to the HDTV, then HDMI out to the receiver?
3. What about wireless speakers? How are they powered?
4. The only way to transmit 5.1/7.1 is through HDMI, correct?


Thanks in advance for the responses.