| TT, Definitely label the tomato whose seeds you are going to save and place some sort of indicator on the stem of the very flower(s) that you pollinated. I just write a code number on the label (to keep the label small) and in my records (I keep a separate journal for that purpose) I put the code number and details about the cross, including a description of the parents and the date(s) of pollination. "Also, if I save the seeds from the resulting tomato, will it grow the same kind of tomato if I plant the seeds from it?" F1 hybrids do not "come true" from seed in the F2 generation, but the F2s vary wildly from the original F1 cross. A small percentage of plants will be very similar to the cross. If you save seeds from them and repeat that operation for several years, you can establish an open-pollinated stable variety from your cross. Otherwise, you can simply repeat the cross to get an additional supply of the F1 hybrid seeds. If you are doing this for yourself, a single tomato can supply you with a good supply of F1 seed that might last you for several years. The book, Breeding New Plants and Flowers by Charles W. Welch, has a chapter on tomatoes. You can get used or slightly shop-worn copies of it for a reasonable price. The book, Breed your own Vegetable Varieties by Carol Deppe, has a lot information, including lots of information about breeding your own tomato varieties. I don't breed tomatoes (I do raise them and eat them), but I have both of those books and frequently refer to them because one of my hobbies is amateur zinnia breeding, and they have information relevant to that activity. MM | 
