Just some helpfull advice!
Read, ask lots of questions and get different opinions.
I was in your same position your in. I made my 55 FW into a 55 SW and thought that my FW experience would be enough. Well Guess what! It wasn't. My knowledge of initial setup and tank cycling was not enough. So I am struggling a bit but I am learning alot. I spend a good hour a day with my tank, mostly because of my problems with my water quality.
If I was able to do it over I would of used sand instead of crushed coral, not used a UGF, bought more live rock instead of fish after a week of setup and cycled my tank for how ever long it took to get my water right. I probably would of added 1 fish after a couple of weeks but no more.
I spent about $200 dollars for initial setup, and about $150 in added items that I needed. $80 of the $200 I spent on crushed coral so I could of saved money if I bought sand. Keep in mind my tank was already running as a FW tank.
As far as the UGF I have always used one in my FW tanks. Everyone on the boards says not to use it. I think it is a big difference in opinion. I am going to leave mine in and setup my 30 gal into a SW tank and not use it and compare. I trusted my LFS for years and took all his advice. He has been very helpful with my situation so I wil take his advice and leave it in.
I enjoy the challenge and love learning from experience whether it be good or bad.
So closing comments, Read, ask lots of questions, be very PATIENT and take your time cycling your tank.
Good luck!