That was actually the one I was planning to get

.
I figured I'd want more flow rate when I eventually make the jump from FOWLR to reef. I read up that I am in the "safe zone" for fish only tanks, but not for reefs, which require more flow.
Protein skimmer was definitely a "wait and see" thing. Was going to get one after the tank cycled and everything was going smooth and I found I needed one.
The reason I decided on a sump is I got it dirt cheap. I only paid 20 bucks for it off Craig's List. I figured that the extra water flowing through the tank would be great to have! And it came with bio balls and stuff.
I think, then, after thinking it over and discussing it, I am going to see about either giving my girlfriend the freshwater fish (she had a horrible accident in her tank where her heater broke and fried almost all her fish

.. and so she is down to a few fish.), or trading them into my LFS for some Saltwater supplies.
After that, I'll plan out the sump and see about purchasing the RO/DI unit. I'll also clean the tank and start off with my first purchase of dry rock. I'll also get some sand, and on the day I purchase my saltwater, I'll also buy the "cultured rock" and set all that up at once.
While the tank is cycling I'll grab my test kits
Then, once the tank is cycled and I got my first fish (probably only have 2 or 3 Ocellaris Clowns), I'll determine if I need a protein skimmer/more flow. And I'll then slowly work towards more fish and going to full reef.
Last questions then:
1. Will the stock lighting be OK for a FOWLR tank? Is lighting upgrades only needed for reef tanks or will my stock lighting not be good for my tank?
2. Should I leave the filter media in the HOB filter? Or should I remove it and just let the water flow through it?
3. How do I go about cleaning the tank? Is there a huge procedure for cleaning it since it once housed FW fish?