I concur, there is nothing wrong with a slow descent. My SS coach has encouraged me to do this on multiple occasions. You seem to be utilizing stretch reflex at the bottom just fine. There is a huge improvement in your form just in the vids you have posted on this thread. I watched your earlier videos and wanted to fix your wrists and on those heavier sets it seems you did that. I think the best advice is just to stay tight all the way into the hole (both with thoracic and lumbar extension) keep your upper back tight, squeeze elbows into armpits and I think sit "butt back" for you as a cue. Oddly enough on your previous vids I noticed a lot of heels coming off the ground on the descent but you fixed it mid set on the last 2-3 reps. Probably thinking too much about leaning over, I think that's normal, you get better breaking at the hips and knees and bending over simultaneously with practice. Also...correct me if I am wrong but it looks like you have been lifting in running shoes this whole time. Some lifting shoes would help you out. Maybe you do have decent shoes on and I just can't tell, if so I am an asshole but regardless, if those are running shoes some weightlifting shoes will help.