MJ pumps are great pump, they work, and are quite... stream pumps like korelias or Tunze, or the MP40W are better because they have a farther spread, also when looking into flow for the tank, you'll want 10x you gallons to have enough flow for all, if you are wanting to keep corals like lps and sps, then you'll want 20x your gallons.
you will need more then flow when you sw and it'll all fairly pricey unless you're a DIY person and then you can save a lot. i wasn't, but i'm moving toward that because of how much you save. It's all research and time and the most important thing, patience, or as the Word call is, long-suffering, and it's exacly that.
FW... you'll need a bubbler, some kind of rocks, perhaps a type of algae, mechanical filtration and some fish... but then you'll look at the FW and SW tanks and ask yourself, "why did i spend so much on FW and all i look at is the SW tank?"