Re: CAT 6 Total Length
You will not see a difference with CAT6. Cat5E has the ability to give you speeds of 1000MBPS at a max length of 295(ish)ft.
Get a router that can do 1000MPBS(or gigabit) connections if you're worried. 100MBPS is still pretty quick.
You network cards in your computers will need to have the ability to work at that speed as well, otherwise it will run at 100MPBS.
Your transfer speed is directly related to the speed of your computer...nothing you can put numbers too, but believe me...it is. If your computer is slow, slow CPU, bloatware, lack of ram, slow 5400RPM hard drive with a small 8MB cache, lack of a quality network card.....they can all hamper your transfer rate significantly.