Hi Cindori and welcome to the forums!

keyclone is a windows program and the number of wows you can run on one box is limited by your hardware and not keyclone. keyclone will also allow you to connect multiple machines together, each managing their keyclones... this will allow you to essentially control a fairly large number of wows, if you want.

as for your specific hardware... if running windows... it would easily support 4 or maybe 5 wows at once. just play with the maxfps and maxfpsbk to squeeze more out of your cpu/gpu

:!: be aware: as a multi-boxer, you WILL be reported if another player sees you. there is no question about this. it is a fact. so, unless you stay in instances alone... you should be aware that GMs will check out all the members of your party that are acting in unison.. and they WILL notice if the names do not match. at which point, they pull out the ban stick...

as for leveling, since you don't have to wait for anyone, you can dungeon dive until your hearts content... keeping all the loot for your clones. i would say this would be faster then normal... exactly how fast, depends on the user