How to choose a good amp

Hi Friends

I'am not really very tech savvy nor do i have a lot of knowledge of electronics specially in the field of music but i have a good ear for music. I love listening to Soft Rock, Blues, Dance and club music and also a bit of R&B. So i basically love listening to everything.
Now i did go hunting for some good amps and i checked out the Denon 1910 and 2310, HK 155, 160 and 255 and also Sherwood and a couple of other brands. I just got super confused and could not decide what to buy. There r so many brands out there and all r very good. Now what r the points to choose a good amp, what is better 4 ohms or 8 ohms? Wat exactly is a frequency response and how do u choose frm this option. What determines the output of the amp, ohms or Rms? The vendor told me that Denons have good treble in them by default and Yamaha has good base. He suggested HK (Harmon Kardon) as they were well balanced. He also said that some speakers may not match with Denons or Yamahas but they all match well with HK. Now all of this keeps on getting more and more confusing. IS this really true? Do amps and speakers really have to match?
I have an old pair of Bose 201 which i do not use at all and also i have an old base unit lying idle. What i was looking at was to get a decent HT amp and a nice set of 2 towers with good center speaker so that can combine all of these and make a home theater setup ofcourse with the bose 201 will be used for surround purpose only. My living room size is apprx 800 sq feet and by budget for the amp is not more than 30k.
Please friends give me ur suggestions?

Thanks

Pankaj