2000 Honda Civic Honda Civic AC Compressor

Air Conditioning problem
2000 Honda Civic Manual 200000 miles

First of all, I am a girl who knows close to nothing about the inner workings of a car beyond how to turn it on and where to put the gas. Needless to say I've been "taken to the cleaners" at the garage on more than one occasion. That said, on a long-distance trip my AC started rattling a bit. Nothing too bad but an audible rattling This was about 3 weeks ago. Now my AC is not coming through very cold. I went to a mechanic (I just moved and went to someone I'd never been to before) and he said I needed a new compressor and wrote up the estimate as follows: (cost of parts first, labor second)

Evac and Recharge: $30, $89
Expansion valve: $39.95, $89

for the following three items they gave me a combined parts price of $545.08 and then separate labor charges
Flush AC system: $44.50
New Compressor: $311.50
New Drier: $71.20

Now I asked about buying my own parts and they said that was fine so I looked it up when I got home and found the compressor, receiver drier, and expansion device in a package for $235, almost $350 less than they quoted. So first, I'm wondering how accurate the labor costs are - it seems to me that if the compressor, drier, and expansion valve are located in the same approximate place and are connected that it wouldn't take almost five hours to complete all three (they're charging $89 per hour.

My next question is if a compressor needs to be replaced is it always necessary that the drier and expansion valve be replaced?

Additionally, I am under the impression that it is necessary to replace one or all of these it's necessary to flush the AC system. But is it really necessary to do an evac and recharge of the freon. - I've had my AC recharged before and it was about $75 and this garage wants to charge me $120. Is it totally necessary?

Phew - I know I have a lot of questions but I just don't want to get screwed, thanks!