yes you can, and you cant really give a number, wii games vary in size from like 2-300Mb to 4.1gb so it depends on the game, but you should be able to fit 2 or 3 quality games on there or maybe in 5-6 crappy ones
Yup you sure can. I'm using a Kingston 16GB. Compatibility isn't guaranteed but they do work. As far as how many games the sizes of games vary widely, as few as 2 as many as 7-8 depending on their size
yeah, thats what we mean, not all games will shrink to such a small size, mario is just one of the small ones, games like Modern Warefare etc are still 3gb+
a chassis is a empty case that you can put any hard drive inside, but the good point of a 2.5" laptop one, is they very rarely (i've never seen one with) need a external power source, mine runs from 1 USB cable alone.