Don't get the Canister, stay with the Skimmer, try to build a sump, it makes for easy water changes and adds to the over all water volume, and a trickle filter? Is that a hang on back filter?
LR, you need more then what you have. around 100-130lbs, or gallons x 2, for that tank. The amount of lbs of live sand you have needs to be determined by how deep of a sand bed you want. If you are going for a shallow sandbed, around 1in, then you are probably ok, but if you are going for a deeper sandbed that is going to be used as a filtration system, then you need to go from 4-5in of sand. Sounds like a lot, but anything in between those #'s can be detrimental to your tank.