Ahem... no, you don't need to plant as many tomatoes as Rita did! I had 20 plants this summer -- I normally plant 12-16 -- and, with more favorable weather here than usual, along with using some different gardening techniques (such as growing some of my tomatoes inside a hoop house), I had way more than enough to make 7 dozen or so pints of salsa, 30 cups of plain tomato sauce, several dozen quarts of juice, several dozen pints of plain canned tomatoes -- and gave away a bunch of tomatoes, while also eating a LOT of them fresh ourselves.
But... you DO need more than one plant
Debbie -- I can't remember... are you gardening strictly organically? I ask this because I don't, and if you do this won't be good advice. Some years back I was a little frustrated that my garden didn't seem to be doing as well as I thought it should, and I asked our local "soil conservation service" director (who happens to be a friend) about it, and where I would get a soil test done. He said something to the effect of "you don't need a soil test, just add some triple-19 fertilizer and everything will grow just great." He calculated that I would need about 5 lbs of the triple-19; however, triple-10 was a lot easier to fine, and a 50-lb bag was really cheap -- and that year I ended up using the entire 50 lbs on my garden and tilling it in. And everything grew like gangbusters (and no, it wasn't all leaves and no fruit... that's when I decided I had been taking the adage about not over-fertilizing WAY too seriously).
I know you're anxious to "get to the next level," but everyone has different soil, weather conditions and so on, and experience really is the best teacher. There are probably other gardeners in your area that could tell you what varieties they've had the best luck with, and your county extension service could also be helpful in that respect. Each gardening year seems to bring some new challenges/problems -- something that did great last year might be a train wreck this year... which is why I am eternally grateful to not be trying to make a living from agriculture.