In the world of salt, bigger is better. Bigger tank means more stability.
Like others have said, the initial setup/cost is the biggest burden, but once tank stabilizes, it's no more difficult than a FW setup.
If you go with fish only, the lighting you have will be fine. A cannister filter can work, you just have to be disciplined in cleaning it often. If not, nitrates can build up real fast.
You'll definitely want to get a skimmer, you're playing with fire without one, imho.
You'll also want to get some live rock to help with bio filtration, although there are plenty of tanks that don't use it. It's just easier with it.
Just do your research and if you've been keeping FW tanks for a while, you'll have no problems with SW.
Good luck!