I would increase the amount of LR
to at least 1.5 lbs per gallon. I would not use any additional mechanical or biological filtration. Your LR
will handle the biofiltration and, if you have at least 4" or so of sugar sized sand, the sandbed will keep nitrates in control. The problem with additional mech/biofiltration is that it tends to produce lots of nitrates. As mentioned before, the cleanup critters in your tank will handle the extra food and other waste. You'll want a good mix of snails for sure. Hermit crabs, although entertaining, are not necessary. If you do decide to use hermits, and I have them in my tanks, you'll want to stick with species that are relatively reef safe such as the scarlets and blue legs. You can do it all with snails though.