I am usually on audio forums for audio stuff so I didnt see this thread earlier.
Bumblebee answered all of your questions so I am just going to add some of my own input.
1. If you really want to save some money you can buy some kit speakers that come with pretty much everything you need and will be far superior to anything that you can purchase built at that price.
here is one that is generally highly regarded:
Here is some more information about it:
Here is the general page for more kits:
Another good webpage for Assemble-it-yourself kits is diysoundgroup.com but these are generally a bit large of speakers as they focus on constant directivity which is highly desirable for big room filling sound especially for movies.
I would also focus on having a 2.1 or 3.1 system first as you will have a much higher quality system going this route than trying to get everything at once.
If you would like to learn more about speaker designs and theory I would read www.linkwitzlab.com
(also has kits available), www.gedlee.com
(Dr. Earl Geddes who did a lot of research on constant directivity), www.musicanddesign.com
(John K is one of the most knowledgable about the dipole speakers out there, right up there with Linkwitz), and www.pispeakers.com
(Wayne has been working on constant directivity speakers for a long time and has many papers on his website about speakers and room interaction.
I would also say that you should look at Onkyo, Pioneer, and Anthem Receivers. They all very in price but in general the Anthem receivers will cost more but you will also get a much better EQ algorithm in the unit. My father-in-law has an Onkyo and is very happy with it, I will also say that it sounds great. Pioneer has ICE Class D amps that can send out lots of power to the speakers but also be quite "green" comapred to you class AB amps which are in most other amps on the market.