Your probably finding a hard time getting a straight answer cause everyone’s environment, Media, lights are different. You kinda have to go with what the plants tell you. If in coco you can judge that better by checking your PH/PPM run off. If in soil it depends what kind and how hot. I feed mine every other watering but I’m in coco so I add cal/mag as needed as well. Perhaps fill out a support ticket with as much info as possible and that will allow for better advice this will definitely help on your second question. I will post a link below. Also provide as many pics as possible this will help people as well.
Hope this helps and the more ya know the better ya grow!