As far as sensation goes, it will depend what technique is used. To preserve sensation, you would need to chose a technique that preserves the nipple stalk, so the T-anchor or peri technique would be your best bet for that. I had double incision and I have full feeling everywhere on my chest except the nipple.
You would have to talk to a surgeon if you have any kind of pre-existing condition like neuropathy. They would be best able to answer your questions as to how it would relate to the procedure.
And as far as completely flat vs. a more male looking chest - unless you've been really working out your chest, you will come out of this surgery completely flat. They can't sculpt the chest to look more male if you don't have the pectoral muscles to do it.