Receivers that work well with Sony BDP-S350

[Red Maelstrom]

I am currently working on fixing up my home theater's setup and am working on getting a good speaker/receiver setup to go with my current situation.

TV: Sony KDS-55A3000 55-inch Bravia SXRD HDTV
DVR: Motorola HD Dual Tuner DVR DCH 3416
BDP: Sony BDP-S350
Game: Xbox 360 Elite

I have almost no experience with audio setups and have asked salesmen at various electronic stores who know as little as i do. A few of my questions include:
1) The blu-ray player I am looking at has an HDMI audio output of 7.1 (awesome), but an Analog of only 2.0; would that mean to take full advantage of my viewing experiences I would want an HDMI-enabled Receiver?
2) I am not at all knowledgeable about receivers; do receivers allow all devices (Game, Blu-Ray Player, and DVR) to have the sound go through them or is there a specific way to connect each device to the receiver?
3) Are "Theaters-In-A-Box" packages a good way to purchase the audio components for superior viewing quality?
4) Which influences the audio quality more noticeably: the Receiver or the Speakers?

I am somewhat on a budget so I do not want to spend $1300+ on the setup (audio only, blu-ray has already been figured into the plan). Any help from those with more experience than me would be greatly appreciated.

Thanks