1. I'd want another layer of plywood. I think Schluter would approve the single layer of 5/8ths for the Kerdi tray, but I honestly don't know.
2. Go to our whirl-famous Liberry
and scroll down to the part what says Kerdi Drain Rough-in. Should answer all your questions.
3. Should be fine if you have a PVC drain.
4. There are inside pipe cutters available as a drill attachment. Can likely even get one at your local Big-Box.
5. Well, you gonna take the word of a guy you ain't never met on an internet site you've never visited over the word of the product manufacturer's representative?
Far as I know that MegaBond is the Big-Box equivalent of Laticrete 317, which is a very good un-modified thinset. Check the bag to see do it not say it meets ANSI A118.1 when mixed with water.
Originally Posted by Frank
Thank you in advance for your help in answering these questions. My apologies if this information has been posted and I missed it in my reading.
All the information has been posted hundreds of times, Frank, and I'm sure it'll get posted hundreds of times more. That's what we're here for.
And since this is apparently your first Kerdi shower, I'd strongly suggest you purchase and download John Bridge's Kerdi Shower eBook before you take another step. Best ten bucks you'll ever spend on a shower tool.
My opinion; worth price charged.