Really depends what your budget is. Revvy's (similiar to the hopper link you posted) are alright but won't keep up with an Ion at maximum speed. For ~£30 you can pickup a decent Egg (Viewloader Evolution II) on these forums which are popular hoppers for Ions - They can keep up with them and aren't hugely expensive either. The higher end are Halos/VLocity's, but at £60+ you might not want to spend that much.
As for the feedneck, you will definately want a clamping feedneck on your Ion - Popular ones are the Q-Lock clamping feedneck or similiar. Again, can be picked up cheaply (£10-£15) in the Classifieds forum.
Have both on my Ion and they work fine together.
-Will