First thing I would do is get a different Ammonia test kit or take some water to the LFS and let them test it.
I doubt the tank still has ammonia that high.
If it's 0.00 like I think it is then you're probably ready to add some Snails. I'd suggest a variety of Cerith, Turbin, and Astrea Snails. If you can find someone with Collonista or Stomatella then that would be a plus.
Remember that snails need to be acclimated well or they will die within a couple of weeks. Just because they are cheap and common doesn't mean they are bulletproof. They are actually quite delicate when it comes to salinity changes.
Don't get too many or they will starve. You should not be in a hurry now so just get a few of each and see how they do for you.
If you have hair algae, this is common. It should decrease as the tank matures provided you don't overfeed and use purified water for topoff and water changes.
Urchins LOVE hair algae but they are also very delicate so treat them well when acclimating to your tank water. I'd stick to the pincushion type Urchins but long-spine are good too. Steer clear of the Pencil Urchins IMO.
I'd wait before adding the Clownfish. Once your tank has had perfect water for over 2 months then I'd get both Clownfish. I strongly suggest you quaranteen them for at least 3 weeks. You can spend the next couple months setting up a quaranteen tank. Beth has an excellent write-up in the Disease forum.
While the Clownfish are in quaranteen overfeed your tank. This will build up extra bacteria so the tank will be ready for the increased bioload. You will want the algae under control before you do this though, the extra nutrients are going to feed the algae as well as the bacteria.