Answer: If you plan to be there for a few years, you can take some steps to improve the soil. I wouldn't try to grow anything in very heavy clay soil or very sandy soil without spending some time and money to improve it. Instead, how about planting in containers? (Then you can bring the containers with you when you move.) You could even use those white plastic 5-gallon pails, and put one pepper plant or one tomato plant in each one. (Not very aesthetically pleasing, though.) Use a commercial potting mix in the containers and, if possible, add some compost and/or dehydrated manure to the mix.
If your soil is marginal, you might go ahead and try. Perhaps you can mix some compost and/or well-rotted manure into the planting areas, and mulch with an organic mulch like grass clippings. The size of your garden is entirely up to you. I space my tomatoes about 2" apart, peppers about 18" apart.
I hope this helps get you started! And I hope you don't get discouraged if you have marginal results this year--it takes time to improve poor soils, and it sounds like you may not be living there long enough to really benefit from all your work.
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