Always like to recommend this link to user supplied tutorials.

http://www.pgmusic.com/videos.user.htm

Especially the one by Dan which takes you through creating a song in BIAB then taking it to RealBand for more track generation and finally into Reaper for final production.

This may help answer some of your questions.
Remember RealBand comes free with BIAB so it's a 2 fer.

And these forums really help the learning curve.
Lots to learn but lots to gain.
Enjoy,
Carkins