Zucchini blossoms are edible (battered and deep-fried), but I don't go to all that trouble.
I don't know if watering by hand reduces the chances of blight, but it can't hurt. It also gives me a chance to pinch off suckers and adjust the ties on the growing tomato plants. The few weeds that do come up are easy to see and get rid of. The first row of green beans is starting to blossom, so I'm hopeful that we'll have beans in the next couple of weeks.