I've spoken with Dr. Schechter about ALT phalloplasty. Initially, he was not offering this procedure, preferring RFF and MLD. I'm not sure what prompted the change but now he is offering ALT.
There really hasn't been enough research done to establish which procedures really have the "best" sensation, but RFF is preferred in this regard. (If you touch your inner arm lightly with a finger and compare that sensation to what you feel on your leg you'll probably notice more sensation in the arm.)
You can find journal articles on the topic here:
Phalloplasty Studies
I'm not aware of ways to prepare for surgery that would increase sensation. Being in general good health is advised, obviously, but I haven't heard of specific ways to improve nerve growth.
With a microsurgical approach, there's no need to expose the clitoris. With ALT and other microsurgical phalloplasties, the nerves from the graft are connected to one (sometimes two) of the main nerve branches in the clitoris. Leaving the clitoris exposed is typically an option with non-microsurgical phalloplasties, such as abdominal or groin flap.
Hope this helps!