Old man willow

[Curulin]

There cartainly used to be Ents everywhere, because in the first age of the Sun they destroyed the remnents of the Dwarf host that had just destroyed Doriath and Menegroth. So Fagorn certainly wasn't the only place they were.
Figgy: Treebeard doesn't say himself that he would like to speak to Tom, but gandalf tells the Hobbits that Tom wouldn't be concerned with anything that had happened, except for their visit to the Ents.
As for OMW being a Huorn, it does seem quite likely, especially from the way we see him act, but if theres no definate answer we could (and probably will be) debating this for a long time yet... Not that thats a bad thing at all
Curulin