My barrel has a lid, and the cords fit right between it and the rim very nicely. Both heater and powerhead are on the bottom (powerhead falls off the wall anyways....)
for your splashing, it looks like you could just pop in an elbow and extra PVC so that the water isn't pouring in at the tip top. Bring it down like six inches.
If your cord isn't quite long enough to reach bottom, you can always use a 1ft extension cord like me
btw SW below, FW above (for the freshwater tank, of course). AWC line is on the right in the back of the pic, not nearly as complicated as so many people believe it has to be--just SW in to double head pump in attic/basement, SW out to drain (you'll probs have one in both places), and the hardest part--connection to tank. I was lucky, only needed a half inch drill bit for the entire thing and made 3 holes in corner of my ceilings above cabinets. (save for prying back the baseboard behind the tank). Wish you luck!