Smaller bugs:
3. I get Job 'canceled: Drop-off inaccesible' spammage in my game, but dwarves have a clear path. They are set to haul stone between z-levels and sometimes they do fine, but sometimes I get spammed with messages. The situation involves usage of ramps, I am still investigating what is wrong.
I would also like to report something like this, though I'd say its rather Major than small.
It seems that building workshops or constructions, as well as removing them, and possibly removing natural ramps too, creates some kind of disabling 'field' around the site of one square larger than the site + unknown z-levels above and below (at least 1, more testing required). Any dwarf that tries to path through the zone on thier way to somewhere else gets interupted. Any dwarf in the zone (as they will be when interupted) will act like they are isolated i.e. will idle there instead of a meeting zone, will only access resources within the zone or natural resources like rivers.
It does seem to clear itself up after a while if you just wait, but it is extremely awkward.
EDIT: More info. I went and started a new fort to replicate this. It seems that the problem only occurs if you have fully enclosed part of the map. I had locked doors at the entrance to the first fort I saw this in, so I tested with and open fort, then added doors. Sure enough, the issue only turns up when you have yourself sealed in by door, construction or channel.