I'm pre-bottom op but have done a fair bit of reading, particularly on metodioplasty. I can summarize, hopefully someone with personal experience, or someone who is more well-read will chime in.
There are several variations on both metoidioplasty and phalloplasty. With both procedures, sexual sensation and orgasm will most likely still be possible.
All versions of metoidioplasty use the growth of the clitoris from T (some guys also use topical DHT and/or pumping). The finished size of the phallus depends primarily on what was there for the surgeon to work with. Some guys don't get much growth.
Because the clitoris is homologous to the penis, it is erectile tisue and can become erect spontaneously/naturally.
Some options/variables with metoidioplasty: With/without partial or complete vaginectomy, with/without urethral lengthening (urethral reconstruction so it runs through the phallus), with/without testicular implants. Some people get a procedure called a "simple metoidioplasty" or "clitoral release" where the clitoris/small phallus is freed from some connective tissues, allowing it to protrude more and "stand up" with naturally occurring erections - but leave everything else unaltered, including the urethra and vagina.
Some people get this and testicular implants but opt out of a vaginectomy. Some surgeons vary the procedure to add more girth to the phallus (such as with Centurion). There's a lot of variation.
Here's a Wiki article.
http://en.wikipedia.org/wiki/Metoidioplasty Phalloplasty uses tissue taken from one or more donor sites on the patient's body to construct a new phallus. Phalloplasty can be done either as an additional procedure after a metoidioplasty (some guys opt to have metodioplasty, and then phalloplasty later, for various reasons), or without metoidioplasty. The clitoris can be incorporated into the base of a phalloplasty, and nerves can spread throughout the new phallus. The old "you won't have sexual sensation after phalloplasty" claim is a myth.
There are several versions of phalloplasty, one of the obvious differences being the donor site(s) for the tissue graft. There is more range for potential finished size of the phallus, depending mostly on choice of donor site(s) and patient preference. It is not erectile tissue. Guys who get phalloplasty and wish for erections have options, including semi-rigid pliable implants, inflatable implants, and external methods like wearing two condoms or using a special kind of wrap.
When viewing photos of any surgical procedure, keep in mind things look very different "fresh" vs. having had time to heal. Also keep in mind some procedures are staged and a photo might have been taken before the final stage. E.g. a photo before a glansplasty (shaping the "head" of the phallus) will be quite different than after.
Wiki:
http://en.wikipedia.org/wiki/Phalloplasty
