"Does the speed of the computer (i.e 1.8 ghz, RAM, dual core processor etc) affect the speed of the ethernet (internet). I wouldn't have thought so..."
not really, it wont alter the speed which things get to your machine, will affect how quick things are processed after receiving them. You should be fine with the above.
price is fair and should do what you describe you will be doing.
If you dont need the monitor, you can probably get them to knock it down a bit more.
