My apple tv 3 is not showing all the tv shows, it did list quite a few but when I looked again there are 4 instead of 444, all the shows are listed on the imac and all play fine.
If you look in iTunes on your computer is all the content visable there? Did it import under TV shows or movies or Home movies? If it is under home movies it will not show on ATV. You can right click and go to getInfo and under the options tab set the type you want.
Oh, and on ATV were you looking under TV Shows or Computers > TV Shows? They will only be visable under TV Shows.
is it best to get a hard drive with thunder bolt connection to keep the films on so spead up things up?
Not unless you have a REALLY crappy NAS. Thunderbolt would be more helpful if you were constantly moving the whole library around. Then it is a big deal, but for the bandwidth you need to stream video it is not going to make a big differnce.