A sump is really the best way to filter your water. I have used Emperors in the past and they worked well. However, when I went to a wet/dry (similar to a sump) with a protein skimmer, and later a sump, I noticed a huge difference in water quality.
With a sump, you can place most, if not all, of your equipment (heater, skimmer, return pump, etc) so the tank does not look cluttered. There are hang on the back wet/dry's and refugiums. With those, you must move your tank forward to make room.
With the equipment you have now, a hang on the back skimmer is your best bet. When/if you get a sump, some skimmers can be modified to go into a sump, so you wont have to buy a new one.
As far as substrate, I (and almost everyone else on here) go with sand. It doesnt trap uneaten food and fish waste as much as crushed coral. That way, the nitrate levels in your tank wont go thru the roof.