Designing Kitchens and Bathrooms - plywood questions for installing granite tile countertops

This might be a question for the tile forum but here it goes...

I'm on the tail end of an extensive renovation for which I've done most of the work myself (and I am very tired :gmorning: ). I didn't have the confidence to lay the granite tile kitchen countertops myself so I hired a guy to do it for me. The one thing he asked me to do beforehand was to install the plywood (these are ikea cabinets that I put it in myself so there was no plywood installed as there often is with custom jobs). So before doing this, I had a few questions:

1) if I'm using 3/4" BC grade plywood, does it matter which side goes up, the sanded or unsanded side? The tile guy will be laying a mortar bed as opposed to using backerboard if that's at all useful.
2) Are drywall screws ok, or should I be nailing the plywood in?
3) The ikea drawer fronts are nearly flush with the tops of the cabinet, so should I use skids or shims to lift the plywood slightly to make sure there will be more than enough clearance for the drawers to open? Anyone out there have experience tiling countertops over ikea cabinets?

That about covers it. I submitted these questions to the tile guy but haven't heard back yet and wanted to get started on laying the plywood ASAP.

Thanks in advance for the help...

Put the B side up. The Tile Council of North America handbook says the plywood should have "dot and dash saw cuts every 6 to 8" on center through the length of the plywood board to prevent warping."
If you can get non rusting deck screws, use them.
How thick is the mortar bed you installer wants to put down? Again the handbook states it has to be 3/4 to 1" thick.