Yes
A 2" Cleanout tee is best above the san tee for the lav. It can be installed behind or even flush with the sheetrock and accessible with a chrome cleanout cover or a plastic access panel.
No. Since you won't have access to those parts, they need to be glued.
We call this a Blind Set. It sucks. First things first. Set the tub in the alcove and get it perfectly level across the back and sides and scribe a line on your studs. Determine whether you need to place the tub in a bed/pads of mortar or just use a ledger board. How we do set up the blind set, is to build the waste and overflow of the tub first. The tub shoe meets the overflow at a san tee at the wall usually. So your trap needs to be set to receive that waste tee. You can measure the center of the tub drain from the corner of the actual tub, not the given dimensions. Get the trap in place but don't glue it together. Then guess the difference in height from the trap to the tub tee. Dry fit that into the trap and set your glued together waste and overflow on top with the tub out, then install your tub to your scribe line or on the ledger. See if the waste and overflow match up to your tub, use the rubber gasket on the shoe too, they need to be part of the measurement... If it does, you just won the lottery. If not, adjust what you need until they do. Once you have it all lined up and perfect mark your fittings to the pipe with a marker and glue it up. But act fast. Set the tub and install your screwed in drain and overflow pieces to double check.. if that checks out, let that assembly cure for a bit. Now you can pull the tub and place mortar if needed and re set the tub with little effort.