I know frost armor scales with level. I haven't noticed it increasing with higher int, but I really haven't been paying close attention to it either.
If you want to go full support, you would also benefit from pyromancy for peace of mind, and haste. Also if you are going to put a point into huntsman for first aid, you might as well put a point into Necromancy for decaying touch. Aerothurge (sp?) also has Teleport, netherswap, favorable winds, and (will have tornado).
To answer your question about int vs wits vs memory. You are usually memory starved at low level. You need 15 or 16 wits to always go first in Act 1. Wits and initiative are usually easy to come by on gear and with buffs. Memory starts appearing on gear starting around level 4 as +1 and +2 around level 6-8. I would focus on putting 1 point into Int, Str, Fin, and Con are at 11. This allows you to use all the gear you may come across until you are level 8-10 when the next tier requires 13 of Int, Str, Fin, Con. Once those are at 11 I would dump my points into Int, until I felt like I was memory starved then one or two points to allow for more spells.
However, first you need to decide what kind of support you want to be, are you an offensive support, defensive support, or something in-between? This becomes important because it will help you decide how to allocate points into wits/initiative. If you want to buff everyone and control the battlefield it might help to have high wits so that you can teleport enemies together for optimal position for your other party members, and then buff them to high heaven to demolish the enemy. Or do you want to be a defensive support and focus on restoring HP and armor, and removing debuffs. If that is the case you may want to have a lower initiative or put your points elsewhere.
I will always opt to go first because that will usually dictate the flow of the fight and the type of fight you are going to have. Also you can always just delay your turn to go last as long as you haven't taken any action during your initial turn.
Hopefully that was clear as mud.
