The wording of Elusive is particular to creatures, so Vine markers will hinder an Elusive creature. Flying is the only way to avoid being hindered by vine markers at the moment.
If you have Bearskin and Elemental Cloak equipped and 2 Corrode conditions on your mage, and you cast Dragonscale Hauberk, you would get to remove 1 Corrode condition. There is a brief period after casting Dragonscale Hauberk when you have only the armor from Elemental Cloak (Bearskin has been bounced, and Dragonscale Hauberk has not been attached yet). During this period, your armor would drop to -1. At this point, 1 Corrode condition would fall off, bringing you up to 0 armor. Then you attach Dragonscale Hauberk, and you have 2 armor total. Note that you still have 1 Corrode condition.