Gnats: Fungus gnats can be a problem, usually indoors though or in a greenhouse, since they don't tolerate wind. Make sure your containers are draining well and not standing in water, which encourages them. Mosquito dunks (Bt-i) can be soaked and then use it to water them when you see adult gnats around. It's the larvae that do the harm in that case, in the soil eating the roots.
Leaf spots are something else, could be insects like thrips, or it could just be damage from exposure to sunshine when wet, or dessicated by wind, etc. Looking at the different plants you posted I think it's likely a physical cause, rather than bugs. Young plants are pretty vulnerable to leaf damage from the elements, but tomatoes grow so fast, they produce so many leaves, they can easily grow out of minor damage.
Overall, your plants look pretty good.
