Currently 12 of the tomato plants (1 cherry, 11 mystery-but-big tomatoes) have fruit on them. Most of the plants sporting big tomatoes have 12 plus fruit on each moving toward ripening. Some of them are still flowering (though it is getting mighty hot and so fruit may not set), some are still getting taller, and some appear to have stopped growing up and out, while producing fruit. Can I assume that those that have stopped growing are determinants and that after I harvest the current fruit on them I should pull them up?

Based on last year, any of the indeterminants will probably produce their largest harvest in the fall (november/december) when temperatures get relatively reliably cool. I'm wondering if I should start some more cherry/other indeterminants from seed now to replace those that turn out to definitely be determinants to make sure we have enough tomatoes in the fall (July-mid-October the only option for fresh is to buy from the store as temperatures are so hot here). The cherry toms we started from seed last year did not produce well even at their peak (7 plants produced less than what most here report from a single plant).

Any advice, suggestions, moral support is much appreciated!!

Since it's so easy to do, you may as well prepare for the worst. Plant a few of every variety seed you have, it'll increase your chance of a fall bumper crop. You can also stagger the plantings over the course of a few weeks. And if you enjoy eating them, then maybe throw in a late cucumber crop while you're at it.

Since you mention awful soil, and perhaps cost consciousness, you can always fill the garden plot with leaves at the end of the growing season. Grinding them up is preferable but not necessary. I mention leaves because they are free, often plentiful, and they do so much good for the soil. You can plow them under a month or two before the growing season, if you feel like it. The type of leaf to avoid is walnut because walnut trees contain a plant growth inhibitor.

If you live within driving distance of the ocean, try to fill a few bags with seaweed. It has just a little NPK, so it would be hard to overfertilize your plants with it, but it has lots of minerals that the soil needs. Just be sure to wash the salt off very very well (both wash and soak?). Afterwards you can apply it fresh, dried, aged.

Wishing you luck with your grow!!

Seaweed, I never thought of that! I live within a bus ride of the ocean. I think a beach adventure is in order and I've never heard of a better excuse to splurge on the fare to get to play in the waves and sun.