1) Yes I've got more room than I could ask for to add more filters
2) It appeared to have a high head pump by the looks of it, yet on the site it said "designed for low-med head pumps"

or something to that effect.......... Not a big conceren to me.
3) could make sure pre-filtration was proper........
4) I as well as most could use more Bio, and Fines filtration..............
What would you offer???????????? I was maybe figuring $1000 at most as the units been setting for 5yrs. and probably would need new media, let alone if the control box works