nanos are always more difficult simply because they are small and things happen rapidly, so saltwater or fresh, your going to have a more difficult time with it.

I am starting up a 7 1/2 gallon ADA cube here in a month or so. So i can document my progress on that if you want. the biggest problem w/ a planted nano is finding plants that stay small enough, and lights that work for you. freshwater tanks generally run hotter, so heat isn't as big an issue, I plan on running a 70 watt viper on mine, or maybe a coralive advanced halide (150) it's overkill, but i am confident i can keep up w/ it. (this will be my first halide over a planted tank.)

as for keeping things heavily planted.. ABSOLUTELY!!!! plant everything you think you want in the tank from moment number 1.

if you dont plant heavily, algae will outcompete your plants. think of it like this. the more plants, the cleaner your water.