All Homasote apparently is not created equal. The stuff I used has a fine mesh pattern on both sides. I didn't spend any time thinking about which side to put down, it was just cut to side and slapped down. Mine is all screwed down with a lot of screws, 700-800 for the whole 12 x 24 main surface.
Edges and around openings got a lot of screws, as well as seams.
All the seams and countersunk screws were then filled in with Speed Finish and sanded smooth.
Finally, it got a coat of brown paint.
After that, the finish fascia went on.