If your tank has been set up since Nov, there shouldn't be any ammonia. Unless something has died, or you've been way overfeeding. Nitrate of 10 ppm is okay, but I would be shooting for closer to 0 ppm.
Water changes should be done weekly and should be at least 15% of the total system, ime.
How to raise salinity is a trial and error thing. But what you could do is not top up for a day or two or three and see what salinity you get. Once it gets to the desired salinity, mark the level in your tank, start topping up again to the mark. I shoot for a salinity of 1.024 to 1.026 at 79-80F.
Who's got Mg tests on sale? I should get another one.
Here are my standard articles I post about water chemistry and chemistry calculators. The last two are on pH:
Aquarium System Volume Calculator:
http://home.comcast.net/~jdieck1/volcalc.html
The Reef Chemistry Calculator:
http://home.comcast.net/~jdieck1/chem_calc3.html
What is Alkalinity?
http://advancedaquarist.com/issues/f.../chemistry.htm
Calcium:
http://advancedaquarist.com/issues/mar2002/chem.htm
Magnesium in Reef Aquaria:
http://www.advancedaquarist.com/issues/oct2003/chem.htm
How to Select a Calcium and Alkalinity Supplementation Scheme:
http://www.advancedaquarist.com/issues/feb2003/chem.htm
Solving Calcium and Alkalinity Problems:
http://www.advancedaquarist.com/issues/nov2002/chem.htm
High pH: Causes and Cures:
http://reefkeeping.com/issues/2005-03/rhf/index.htm
Low pH: Causes and Cures:
http://www.reefkeeping.com/issues/2004-09/rhf/index.htm