Do you need to finish a cement board for a shower like you would if it were drywall?
Yes... Cement board can get wet but it's not meant to be soaked as it would be on a constant basis in a shower. You'll want to tile it.....
Or since you already are going to have thin-set.... Use mesh tape and mud the tape in with thin-set....same thing.... works just as well. The primary reason for taping and mudding the joints is keeping moisture OUT its not a leveling out or cosmetic issue like drywall, make it flush and cover the tape with material and your ready to tile. DO NOT USE reg drywall mud it is not for wet applications.....
You should have tar paper between the cement board and the studs to keep the water from the framing since as no one else mentioned, CEMENT IS NOT WATER PROOF. It is not even water resistant, ask anyone with a basement and poor drainage. The water from the shower will not damage the cement board, but it will get through it and affect the wood unless there is tar paper or some other moisture barrier. When you install the tile onto the board you only need to spread the mortar on the same way you would if you used a traditional scratch coat instead of the board.
Yes..2 reasons..so moisture cant get behind the wall...and it's prevent fire from spreading faster if that wall were to burn. Use dura bond and seam tape just like you would with drywall.
