Decomposed: All of these are good advice and if I may add my .02 as a kid raised on a farm in the hills of NC and as a master gardener (whatever that is LOL): #4 yes!! When you have your planned garden area (raised or not) may I suggest getting a couple of cattle panels from Tractor Supply to address #7. Cattle panels are 4' x 16' and are $20 each (roughly) and made from galvanized steel. Arch them between T-bars and have them about a foot above ground. Two side by side (tied together with aluminum chain link fence ties or wire of your choosing) will make a nice trellis and provide excellent support if you train your tomatoes - assuming you are growing heirloom's - most of which are indeterminate vines.
I am not sure about the rationale of the 90 degree bend referred to in #8 unless someone cannot dig a deeper hole. Tomatoes will actually create roots from everything planted below the soil. Speaking of soil - if you have not done so already then I am sure you are planning on testing your soil. I am lucky that here in NC our AG goes it for free during in the off peak. NH is not free yet $20 is reasonable. http://extension.unh.edu/resource/pricing-list-all-soil-test-options
Lastly, when I plant my tomato seedlings I always add a mixture of worm castings and Epsom salt to the bottom of the hole before transplanting. The Epsom salt provides magnesium for better tasting maters' (add some calcium nitrate also to avoid blossom end rot) and worm castings dramatically help with the plants nutrient uptake. I downsized from 70+ plants over the years to only 18 planned this year. Early Girl (volunteer from last year), Potato leaf Brandywine, Black Krim, Cherokee Purple, Mortgage Lifter, Mexican Midgets (super sweet cherry) and my favorite Paul Robeson. I also make my own foliar sprays - worm casting tea is a favorite - to help with plant health.
I am an urban farmer now as I have commandeered what my city calls a paper alley that is 200 x 15 and 100 x 15 has full sun. Here is a pic of my tomato trellis:

One more thing - get a patch ready to grow some garlic!!
Have a great day all.
PEACE