It worries me because this is the surgery route I would want to take.
But apparently post-op it is too small to be able to do full intercourse? 
Is this always the case?
Can it be lengthened after surgery to make it long enough?
Thank you! 

It depends on how much length and girth you have prior to surgery.  Meta doesn't give you more length so much as free up the length that you already have.  I am inclined to think that penetration is a rare ability with metoidioplasty.  Beyond that, all I have to offer is hearsay: I have heard of some guys being able to penetrate post-meta.  Of those guys, I have heard some say that their length and especially girth are not sufficient to bring either person to orgasm (using penetration alone).

I'm not healed yet, but I personally think I will be incapable of any sort of penetration.  I measured at 4cm (1.5") flaccid from pubic bone to tip of glans prior to having a meta; my erect length was not much different.  These measurements were taken along the top side of the penis.  None of this length protruded from my body, thanks to the suspensory ligaments and short urethral plate holding it down.  The meta I had freed my penis so it is capable of sticking straight out from my body; in this way it looks more prominent.  The biggest difference I can see is that, prior to surgery, I could not see my penis when standing up with my legs together.  Now I can clearly see the head.  However, I do not think that surgery added any actual length to the organ itself. 

I am not sure what my final usable length (how much it sticks out from my body) will be, given the swelling and retraction that I currently have.  Presently, it protrudes about 1/4" from my body at 24 days post-op.  I am to start pumping at around 4 weeks post-op to help with the retraction.  Prior to surgery, I could pump my penis out to 2" (from pubic bone to glans) into a 1" diameter cylinder.  I also have a fat mons pubis that is hiding some length.  The surgeon recommended liposuction and a mons resection as a revision to help take care of that; losing weight would also help (5'4" and 143 lbs).  Beyond that, though, I don't know of any way to make a meta longer, other than opting for phalloplasty.

*Please note that all of my measurements were taken carefully with a ruler.  They are not a visual guesstimate.

It will depend on your growth, but I would say for the vast majority you might be able to penetrate a little bit, but not much.  But since there are many ways to have and enjoy sex, I'm sure you can find something suitable to please your partner and yourself.    .


Jay

No. Don't believe what you hear, it would be terribly awkward and useless.

(I know, bumping an old topic.)

Caveat emptor: I have not yet undergone a metoidioplasty myself, but I intend to do so.  And I am inebriated as I am posting this.

Somebody once told me it's not the size of the shovel, it's where you dig.  "Penetration" can mean many things.  What we define as "intercourse" is certainly not the gold standard.  There are also many women who I have met (and had the strange circumstance of being able to discuss this awkward matter) who genuinely prefer small penises.  Though I am not a woman, but rather a bisexual man, I have a great appreciation for small penises.  Nerve density, maybe, or just not being bothered by the fallibility of human flesh to a certain point, but I've never understood the obsession with length.  (And some people whine about length too, i.e, not enough girth per length to give them the perfect sexual object who probably doesn't exist...)  Welcome to the world cismen live in, there's still body shaming and inadequacy over here, but less support network and less room to get mad about it.  That probably sounded very patronizing, and I don't claim to be an expert on all things gendered life, but I have my experiences and perceptions and they count for something.

If somebody is going to judge you and reject you on the size of your penis (small as it might be,) they are not worth your time, effort or physical prostration.  I mean, after surgery, at least you have one. 

(Also, TMI: Oral.  Seriously.  Giving it and getting it.)

It can seem like a faustian bargain, FTM bottom surgery--length and girth at the expense of sensation and spontaneous arousal, or smallness with sensitivity and hands-free erections.  If you're emotionally/psychologically capable of being "stone butch," indirect physical pleasure as completely satisfactory, then...it's 50/50, maybe moreso for some in the direction of phallo.  I could not be "stone," I tried a few times, I hated it and it caused internal turmoil.  So for me it's meta or perish, size be damned. 

My experiences are not everyone's, I know.  But size and intercourse are seriously miscalculated, underestimated and overrated.