It will help. Remember that the programs are designed that way for a reason. I tend to err on the side of not making changes.
BBB is a very popular supplement. Personally, I would ease into it. You might not need to, but there is no need to hurry. It is important to understand the principles of your entire program. If you understand the purpose of BBB, and it fits with your goals, good.
Supersetting pulls/rows is fine. I had no problems supersetting pull-ups between all main lifts when I went 4x a week.
As far as replacing them with similar lifts, I don't think it is the best idea, but I'm admittedly pretty ignorant on BBB variations without any books in front of me. It was never my favorite choice for supplemental work.
That is not a knock on it. It's awesome for a lot of people. I'm just explaining why I didn't answer that question.