I'm not picturing your vent problem very well. A picture that is 800 pixels or less would be nice here. You can add them as attachments.
You can always go higher with a revent.
Adding the wall faucet is always a challenge. The studs may need to be moved or cut out, the vent may need moving.
If you run the shower head in the ceiling, don't insulate the pipe. Make sure the insulation is above the pipe. Not below. You want to trap the warm air.
Leaving the shower drain where it is can be good. You will need to replace the drain itself to work with the new pan.
No big deal though.