Also, is it possible to put a sump below the tank in a cabinet?
Not to sound smart or anything but yes thats where most of us keep them. Others plumb them from their basement or from behind a wall and into a special fish closet/room.
For a 60gal tank I would have a sump no smaller than 20 gal
Hardware, Since you said you want to get into reef Ill factor that in.
High output lights. Either VHO
. Shoot for 300W of florecent light or 2 150W MH
and 100W actinic.
Powerheads (number to be determined by flow patterns around rock and corals)
Test kits for ammonia, nitrite, nitrate, ph
, alkinity, calcium
assorted fish buckets
75-100 lbs of live rock
3"+ depth of sand
Overflow (if your tank is not 'reefready')
Return pump (if you use a sump)
Misc plumbing supplies to connect sump to main tank