Man, I love these sites...what a wealth of information I have received from all of you already-thank you!!!

Cut out our old cast iron tub and have pretty much everything down to the studs in the bathroom. Putting in a Kerdi shower with tile surround and floor.

Used 3/4" treated T&G ply for the subfloor. In regards to the floor, should I throw down some roofing felt before moving forward with the Hardibacker or is the treated ply sufficient? Would I run that underneath the pan area as well?

Does one typically used Hardibacker underneath the pan or only outside of the pan area where the floor tiles will be laid?

I'd like to insulate the walls while I have them open, one being an exterior. What's the best way to avoid the dreaded moisture sandwich?

Thanks in advance,