As mentioned in Andrews post, you can regulate some of what you want to do with the Song Settings dialog. Two check boxes in particular will affect how things play - one being the Vary Style in Middle Choruses and Allow Embellishment of Chords. The others can also change how things get played if you want/need any of the specific options. I generally turn these off by default and manually tell BIAB when and where I want these things by the use of part markers and the chords that I input into the bars. As Andrew said, these are checked by default and I'm not sure what overrides have priority between Song Settings and F5 Bar Settings. That info is probably in the manual somewhere.
Good luck.

PS - you don't want to hear this, but some of what you want to do is easily done in Real Band, included with BIAB. There, you are now a newbie in 2 programs. I'm not sure that really helps.