You might try a 60/40 rubbing alcohol to warm water spray. Gentle on plants and should get the flies pretty well. Soapy water seemed to make my tomatoes unhappy when I used it for aphids, alcohol does not seem to effect them thus far, but only been spraying it for a few days.

Looks like too much water. You can just re-pot into a dry mix or try wicking the moisture out by placing the pots on an absorbent material or by using a shoe lace. I've, also, had good success by stuffing paper towels into the holes at the bottom of the pot.

The pot I see reminds me of the plastic ones that have a saucer attached. If this is what you are using, make sure that water is removed from the saucer after each watering. That water will wick back up into the medium making it constantly moist.

The photo you posted of an aphid looks like a fly to me. If you have small flying insects that multiply rapidly, it could be fungus gnats. An application of BTi, followed by another 7-10 days later should take care of them. (Dissolve 1/4 of a mosquito dunk in 1 gallon of water.)

I just had another thought. The curling of the leaves can be caused by sucking insects on the under side of the leaves. Mites can be so small that they can't be seen by the naked eye. Place a piece of white paper under the leaf and tap it. If you see little specs it could be mites. Run you finger across the specs, if they smear, they are mites.

I also think it may be too much water or too poorly draining mix. Tomatoes and peppers both like as much sun as they can get, are yours in the full sun? If they are outside where the predators can get to them you will have less insect problems. Al