The yellow spots on your plants come from a deficiency but it appears that it has fixed itself it has not look like it's gotten any worse than when it first started
Yes I've started adding heavy 16 formula they sell for flowering. Got some samples so said why not. Those buds look huge, that's more or less what I'm trying to determine based on my buds now how large they might become
I do see some frosty white in not sure if you can see in the pictures but I dint think I'm there yet too many white pistol hairs. You grow great stuff looks dense and nice
If you want an ounce or two per plants you may want to let your plants get at least 18 inches tall and go through at least one or two training processes
I'll keep that in mind for the plants I'm vegging now there are five. When they went into flower they were about 2 feet ta from the soil, I did do some LST, later than I may have wanted to but enough to have topped and make them somewhat bushy