I don’t pinch back the orange cosmos; they are a lot more airy than the other kind. I pinch back the hybrid ones (’Sensation Mix’, Etc.) to make them fuller, though.
Don’t pinch back the tomatoes yet, either. But take off the first set of blooms when they come about. I know. It’s hard. But you don’t want a tomato setting fruit too early in the season; it’s not strong enough to support it yet, and early fruiting is a sign of a ‘stressed out’ tomato plant.
I always plant my tomato plants very deep ... most of the stem goes underground to grow a strong root system. I also pinch the suckers off until the plant has developed a big, thick and strong stem, then I will let the plant ‘branch out’ a bit.