Wawary
My horizontal pulling exercises include face pulls. done in a seated position using the low cable row machine, and seated lat rows. In general, though, I prefer vertical pulls due to a lower back fusion.
I usually have military presses in my routine twice per week but am taking a break from it this cycle. My shoulder routine this cycle is designed more to hit the shoulder stabilizing muscles to balance things out.
I think your program and exercise and rep choices are good. I cannot comment on volume as I do not know what kind of condition or state of body building you are in and sets/reps is very dependent on that.
I change exercises up only when changing cycles, not during a cycle, and even then it may be every other or every third cycle. I like to get some neural adaptation on my exercises to help increase the amount of weight I can lift. You have to get strong to get big.
For legs, I stick to leg extensions and leg presses because of my back issue. Despite many nay sayers out there, leg extensions can be a very effective leg isolation exercise if you need to avoid risking back issues. Without that issue I would still be doing squats and deads. Normally not a problem for most people but I do not want to bend the rods inserted in my spine.
I do not do a week of 12's then a week of 8's, etc. I do a day of 12's then my next workout is a day of 8's etc.
I would say to go for it and let us know how it works for you.
O&G