I got the 9005 because mine is a planted tank and I don't want too skim too aggressively but if I were doing it over I'd get the 9010 just because it has a bigger collection cup. I have to empty mine every other day (without any livestock yet) so once my tank is stocked I'm probably going to have to end up drilling a hole in the collection cup so I can hook it up to a waste collector.

The tunze mounting kits are somewhat confusing. My tank has euro bracing all around so the skimmer was kind of unstable. So I siliconed some short plastic rods (cut from plastic coat hangers) onto the back of the skimmer to brace it and keep it level. It worked well.

It's really just a good venturi needlewheel skimmer made to hang in the tank. Mine pumped out quite a few micro bubbles for several days while it broke in but none since.