Volumes adjust like any other instrument - the little spinners next to the selected instruments along the top area of the chord sheet, below the menu bar. Some styles will override changes you make and that is another story.

On the line in BIAB that has the style, key and tempo settings there are 3 boxes with numbers, the farthest right is the number of choruses. It defaults to three. Click and pick from the dropdown. Or if you want multiple choruses on one big chord sheet, Unfold the song.

Bars shift to a new line with the addition of a part marker (A or B for basic songs, you can have others) so if you click on the bar number 10 it should shift it to a new line. To undo that later you can click the bar number again until the part marker goes away and the line should revert. There are some rules as to when and why lines split to a new line. Check out the manual for info on that as well as setting this feature off altogether if you like.

Good luck.