holy questions batman!

first, before you switch to 12/12, you want your plant to be sexually mature. this means either preflowers, or non-symmetrical nodes.

second, no. don't cut the leaves. leaves=energy for plant, even when damaged. 50%+ damage/yellowing means you can remove the leaf, but many growers never cut anything until harvest.

third, LST. Low Stress Training. train (tie) the top of the plant so its lower than other nodes. this will make the lower nodes compete to become the main cola. research it on here, you'll see.

fourth, blow the $7-$10 to buy Jack's Classic Bloom Booster (or similar bloom booster at your local greenhouse/gardening store). cheap and effective. wouldn't hurt to have a high-nitrogen veg nute either. bet you could get both for under $20 locally.

the leaf close up looks a bit heat stressed. if you've moved your lights already, good job.

read, read, read

stay safe
-GG84