A couple of questions about a $850 gaming build

Approximate Purchase Date: this week
Budget Range: around $850 (for the box itself)
System Usage from Most to Least Important: gaming, web development, hobbyist graphics programming, surfing, recreation, etc
Parts Not Required: any peripherals
Preferred Website(s) for Parts: don't bother (see next line)
Country of Origin: Ukraine
Overclocking: won't / not that enthusiastic
SLI or Crossfire: nope (want to stuff all of that in a mini-tower)
Monitor Resolution: 1920x1080

Current lineup:
* Intel i3-2100 3.1G CPU
* ASUS P8H67-M mobo
* 8G DDR3 1333 RAM
* ASUS Radeon HD 6950 2G GPU
* WD 500G SATA3 7200rpm 32M HDD
* ASUS SATA DVD-RW


Question #1: Am I not making a mistake by choosing an i3 CPU? I'm not planning on doing any serious video processing. I figured that it won't be a bottleneck in gaming, so chose a good GPU instead. And I really, really, really don't want to fuss around with overclocking.

Question #2: Am I not making a mistake by wanting a mini-tower? I'm looking at this Chieftec specifically: http://www.chieftec.eu/index.php?id=390&option=com_cont... - will the graphics card fit? any other concerns I should have?

Question #3: What (full-sized ATX) power supply will be sufficient?