"Will the same blossom clusters that have already fruited and been harvested re-blossom and fruit again? "

No.

"produce throughout the season until frost, but is that only on NEW growth? "

Basically yes. Every now and then a new a new cluster may develop down on old growth stem but it is rare.

"Does it matter if the tomato was broken off at the "knuckle", or twisted off (leaving the "star" on the vine)?"

No.

Dave

New tomatoes form on new growth or branches. When pruning/trimming, removal of all growing tips would restrict new growth and by default new tomatoes. On my jungle, new growth is occurring on top where the tips are, and that is where the blossoms are as well as the new little tomatoes. Occasionally, a side stem emerges and produces something new, but this is rare on a large bushy mature plant. I believe the commercial growers will confirm it is the growing tip, that is continuously lowered or reeled down, in a commercial setup that delivers new production. In the fall, I believe some growers will remove a growing tip as a means to redirect the plants energy into existing tomatoes, to hasten ripening to beat old man winter (first frost), rather than starting new little tomatoes. I have read some accounts here, where young plants exposed to severe storm damage, are able to recover from a lost tip. This is unverified. The youth of the plant might have played a role, or maybe the tip was just damaged and not severed. Removal of all growing tips is a good way to stifle production, in my opinion. Most "cage" growers (I am one) let their plants grow up and out the top of the cage, then flop over and out and grow down the side, outside the cage. Not sure what your neighbors might think, it is just a big green plant, what the heck right? I would think you could thin the lower internal branches without much negative consequence.

Pruning reduces fruits. That's about the size of it. If you need to prune because the plant is getting unwieldy, that's the price you pay. Of course, if the plant was unwieldly large before, that price may not be dear.

But that's right. Pruning can also be used to discourage new fruit specifically in order to ripen older fruit in a short season, and it can be used to concentrate energies into a small number of fruits to make them bigger.

Thanks for the input guys.

When I have a back yard I can afford to let the new growth branches go wild, but for now this is how it has to be, but at least now I know what to expect!

In my experience, pruning off growing tips makes the plant produce new ones in very quick order on the next lowest available node. You really need to stay on top of it. Unlike some plants that get bushier and fill out underneath when you top them, tomatoes are really determined to grow vertically.