wow that is one really high volume workout

you should probably stop jerkng the bar during deads.

i will keep an eye on your progress using this routine

of course u are feeling it in low back, ur lower back is verry rounded during conventional deads

deadlift is all about hip hinge. u should feel it in the hams and glutes, maybe some quads during the first half of movement. there is not supposed to feel in lower back, if u have, u are doing smtg wrong

i recon u to lower the weight and practice form again. deadlift indeed takes very long time to master form. i suggest doing romanian deadlift so u undertand the concept of hip hinge

i doubt that gonna do much for you. i would say if ur bf are less than 20% keep bulking, if u are above 20% keep cutting. i would say mini cuts are for bodybuilders who are competing for an event etc. the strongest reason why i object this is you are running a linear progression strength routine, and that cut gonna hinder your progress. i have no experience in cutting, this is just my input

check it up with sports physio or chiro, stop any exercises that induce the pain.

what are the optional exercise u gonna include? and 6 sets of pendlay row i bet u hate it lol

u should really becareful with ur shoulder man. it is not pleasant to have injured shoulder and aint doing upper body workouts for months.