Weird gate near the gate of Thal in central thanalan?

[Phyllo]

By deleted I meant that the area is no longer accessible.
Is that so? I should check it out then ^^

[Nialle]

That I know for the crossing, but at least the crossing have some Npc that explains it (I still don't understand how the hell we get from north shroud to coerthas trough a way that previously was a huge mountain wall and now some nice little road near the river xD)

That entire connecting area was blasted by Bahamut, though the damage is most obvious from the Shroud-side. So that's why it's passable now.

[Velox]

There is also a gate in Gridania near the Lancer's guild, which I can only theorize is the road to Ala Mhigo.

Ala Mhigo lies east of Gridania. The road to it is most likely the road that currently exists in Larkscall (East Shroud). Next time you do the Wrench in the Works FATE just keep going east and follow the road, there's an invisible wall blocking it off, but you can clearly see it curve around the bend and keep going into the distance.