Pruning is taking off branches. Defoliating is taking off leaves only... from my knowledge. Tons of stuff online about doing it and not doing it. I second the ones who say don't do it. You may survive it, you may produce some, but chances are you won't know what to compare to. They may do OK but you won't know what normal is. If change happens that normally happens but it's drastic, you may think it directly related toward your actions, pruning. It may or may not be. The only thing you have to loose is your yield. If that's not important, prune away. At this point, week 3 i'm guessing, you don't want to be doing pruning or defoliating, something you may learn the hard way. Last pruning you should get done before flower or in first week IMO. If you do stress your plant out, it may produce hermaphrodite pollen and/or stunt your plant. If your plant stops producing bud to repair itself, your yield will be effected. If it puts more energy and nutrients into making leaves because it notices some gone, your yield will be effected. That set aside, pruning, topping, and defoliating are strain specific. Some plants love it, some hate it. If you don't know what loving it vs hating it vs being indifferent look like, how can you make a logical decisions on whether or not to do it? That's why they say to wait till you've been around the block. Looks good though, should be some good smoke. Plants look healthy.
For nutrients, FF will work just fine. Next comes experience. The best grower with the worst nutes will do better than a new grower with the "best" nutes. Fox Farm will do the job for you as good as Advanced Connoisseur bloom will i'm sure. Keep it simple for now and get the hang of it. You can buy to your heart's content, but it would be kinda like buying a Maserati if you don't know how to drive a manual. The best nutes won't make you a better grower. I've seen amazing bud grown from General Hydroponics GMB. My advice- keep it simple and less is more. Have fun