The biggest issue with cloning is over/under watering. If you keep them too wet the stems will turn to goo. I use a dome, rooters and clonex. I don't scrape the stem i just slice up the stem a bit, get it liberally covered in clonex then stick it in the rooter tightly. I don't have water...
I run 400ppm thru veg with coco. Cut it in half for first 2 weeks. Bloom I run 500-600ppm. You can go way lower with ppm in coco with multiple waterings.
Another option is to Supercrop (squish stem and bend down without breaking outer skin of stem). Normally I will do this instead of topping when they get too tall. If the height is from a single main stem then top away.
3-1-2 for veg
1-3-2 or 1-2-2 for bloom
Supplement calmag with RO water or when growing in coco coir.
This is only a general guidelines but what's important is you need a lot of N in veg and very little N in bloom (less the further into bloom).
Ive changed P and K around a lot and haven'tseen...
It seems from the pics your trichs aren't all cloudy yet. I pick mine when almost all trichs are milky white and some here n there are still a little clear. Usually at this point there will be a few that start to have amber spots in the gland heads. Go get yourself a 60x-100x loupe. Never go off...
I use coco as well. Give Dyna gro a try. Easiest nutes I've found and they work just as good as anything out there. For veg stage, use foliage pro and for bloom stage use a mix between bloom and grow. You will need a calmag supplement as well.
IMO the only way you should ever go above a 3 gal pot is if you want to water less frequently (which eliminates the benefit of coco) or you're growing over 6' plants. My plants range from 4-6 ft in 3 gal containers and i autowater 4 times a day.
I run coco and just finished a comparison. I've found that as long as you have very low N at the end of bloom the flush doesn't do much. Without a flush the ash was black but had no Chem taste. With 3 day flush ash was better but not other noticeable benefit.
I tried this once with God Bud (which is bushy to start). The clones grew the same as regular besides they had a later start. They were also very bushy with almost too many nodes. I had to bonsai them a bit just to improve airflow. Besides that no real difference imo.