Very nice!
By the way :welcome to Nanotank.com!
Well for a 2 gallon tank I don't a clown fish is the best bet. Actually I don't think any fish would do well. Sexy shrimp and other inverts can do OK. Anemones are another thing that wouldn't do well in just 2 gallons. Try your hand at a few inverts to get your feet "wet" :roll: . Maybe a snail or two, a hermit, and a sexy shrimp or two? For top off water use fresh water, not more salt water.
For testing I use Seachem test kits (they are very mad scientist like and I don't mind them at all) but I hear API kits are pretty darn accurate and easy to use. Testing more is always better.
I would leave the rock in and just wait for the ammonia and nitrite to spike up and then hit zero before adding in any living creatures (could be a couple days to a couple weeks).
Good luck!
P.S. Try reading a couple build threads here in the Pico section to get some ideas for your tank!