Thanks for all the comments.
How to progress with this was going to be one of my questions.
I was thinking of making progress in terms of number of reps. So now I'm using a 10kg plate and then 5kg dumbbells (sooo light, but as you all know, it hurts like hell). So I have started with 8 reps per exercise (24 total in one set). So progress will come in terms of additional reps when the time is right, and when reaching 10-12 reps (if that day comes), then upping the weight a notch and start back at 8 reps.
Does this sound logical?
Also, do you think that focusing on a powerlifting style flat bench, and good form seated rows, plus the shoulder shocker is sufficient for shoulder training? I am following the HCT12 program - basically an ABAB routine (upper then lower, day off, upper then lower). So I train chest and back - with shoulder shock - twice a week. I feel that this is enough. Thoughts?