Thanks to Ergo Sum - I talked to the Water Company!

Nitrates = 1.8 ppm (would need to dose up to 20ppm) - an average cycled tank will generate what you need each week

PH out of the tap = 7.2 - 7.3 (wouldn't this increase after 12 hrs or so as
gases are lost???) - the pH would actually decrease over time in an established tank, and more, if there is driftwood in the tank.

Water is Semi - Hard = 6.5 grains (what does that mean?????) - it refers to grains of minerals, but it depends on how they are measuring grains... per gallon or ? ... and it depends on the scale they are using.

Is the 6.5 my General Hardness? It's not my KH is it???? GH and KH are different. Here is a good article explaining that and more about water.

http://faq.thekrib.com/begin-chem.html

Keep in mind that what you use in ferts may already be present in the water, so try growing a few easy plants and see how they do. If they present symptoms of deficiency, then you will know what your water is lacking or what more the plants require. Not all plants require the same or as much fertilizer. I tried different ferts to see how my plants would react and it turned out all I really needed with my water is a bit of phosphorus and iron. Why add more than you need? Here is a good link for deficiency symptoms.

http://www.csd.net/~cgadd/aqua/art_plant_nutrient.htm

1. Yes
2. Yes
3. Probably. Most piped water is under pressure which keeps gases dissolved in the water. Once it comes out of the pipes and the pressure is released, the gas is dispersed. Try aerating the water for 15min and re-test. Leave some out for 24hrs just for curiosity's sake and re-test.
4. Grains are a unit of measure. Hopefully, it's grains per gallon (1 grain per gallon is also known as a Clark degree) which equals 17.1 mg/L (or ppm). If so, then yes, that is your General hardness, a measurement of Calcium and magnesium salts. It means what it means, which is confusing because there are various ways to measure hardness (obviously), but in general, when aquarium hobbyists state a hardness as 1 through 15, it's a Clark degree or grain per gallon. If they state it's 17 through 300, it's probably measured in ppm or mg/L.
Hope this helps!

-be