Wow! Those look really nice! I am not sure on the yellow, but I suspect it's some sort of nutrient problem. The leaf curl is most probably an issue with cold. I had some a few years ago that I had planted and it got close to freezing one night. The leaves curled quite a bit after that. They usually straighten out after a bit.

How long before you can transplant these to the garden?

They are all stressed right now for various reasons - size, leggy growth, container size, excess watering, root bound, temps, exposures, etc. The stress is causing all your symptoms. But they will likely recover once they get settled into the garden. Assuming that will be shortly then just transplant all of them to the garden, deeply to just below the top set of leaves or trench them in well.

But if you still have more than a week before they can go to the garden then the best you can do is transplant them into much larger containers with a good potting mix and some mixed in nutrients, as deeply as possible, and cut back on the watering.

Did you grow them from seed? If so, next year you might want to wait a bit longer to start your seeds. ;)

Dave

These tomatoes are going to be grown in 5 gal pots. No plans on putting them in a garden; my landlord is fussy. I'd have to tear up the lawn - he's not going for that.

These tomatoes are going to be grown in 5 gal pots.

That's fine as long as you understand the problems and limitations associated with that approach. Personally I'd recommend much larger containers if possible for many less problems.

But either way they need to be planted in those 5 gallon buckets DEEPLY and as soon as possible and then monitor your watering very carefully.

Dave

Now my Roma tomato plant is half yellow on top, the rest of it light green. This is irritating (it is still very small...I'd say certainly not taller than 4 1/2 inches). New growths are all twisted and dry at the tips, drying back down towards the stem.

Additionally, several of the plants are drooping during the day and rebounding at night (when I bring them inside). Some of their leaves are beginning to develop burn marks. This is absurd; it's early March and they aren't outside for more than 7 hours a day in direct sunlight. It definitely seems to be lighting related though, as they all look fine in the morning before I put them outside in the sun.

What is going on here? I hate it when seedlings immediately start to have problems straight from the store.

Root bound, as mentioned above. drooping during the day and rebounding at night is a clasic symptom of a root bound plant.

Lift one out of the little container and look at the roots. Likely there is little left in pot except roots. They need to be transplanted.

Dave