(1) wireless, b: 11mbps rated (but around 5 in normal use), g and a (a is not popular) 54mbps rated.
(2) in my view, all those "faster 1m, 2m, 4m" connection are just "con" because all the upload speed are the same as 512 service, 256kbps.
1m and 2m may improve your on-line gaming performace slightly (I am not game, but I even doubt this is true becuase other parties can only upload 256). You may download films faster, but how much money you have to pay for legal download?
If you have money to burn, get the 4m, but if you want to spend in value for money term, get 2M becuase the price is the same as 512 for most ISPs