Besides needing a little fertilizer to green them up, your plants look healthy. The heat is probably making the leaves defend themselves a little by curling. The Osmocote is slow release. Give them a dose of a liquid or water soluble fertilizer and you'll see faster results.

Agree. Tomato leaf roll is a physical response to stress. Remove the source of stress and it goes away. It poses no threat to the plant if the cause of the stress is fixed.

The growing method you describe has several possible stress causes in it: containers, containers of unknown size, the growing mix you are using, the frequent shallow watering leading to shallow rooting, keeping surface soil wet causing even more shallow rooting, the feeding regimen you are using, etc.

I would suggest some reading over on the Container Gardening forum here and a review of the 'growing in containers' discussions on this forum since trying to grow in containers is a unique form of growing tomatoes with its own set of needs. The search will pull them up for you to browse through.

For example, common recommendations are containers of 12-15 gallons minimum, soil-less potting mixes only, weekly feeding with a full spectrum, well balanced fertilizer, adding beneficial soil bacteria if using organic fertilizers so they can work (otherwise you need to use synthetics), less frequent but deep watering to maintain consistent soil moisture levels, etc.

From the color in the photographs your plants could really use a good feeding. In a container you can't count on compost for nutrients since there is minimal if any soil bacteria.

Dave