Does anyone know if you will be able to send mail to a friend's town from your own post office like you used to be able to in City Folk? It was a total bummer you couldn't do that on New Leaf!

Yes you can once you open up the airport for visits.

Eggsellent!

I tried to send something to a friend from my town to theirs and the only options I'm getting are "A resident here" or "my future" self"  :/  

You may have to have them visit first, or vice versa.  If that doesn't work, you'll need to add them to your "best friends" list, though I don't think that's necessary.  The first option should be sufficient.

That was it,  it changed once we did online visit versus local.  Thank you!