While I see no reason as to why the gauntlets couldn't be used as standard gauntlets, I can't say as I know what type of weapon they'd be. As it doesn't specify, I would assume they function as "Good" quality items, at least in terms of weapon damage and speed.

Personally in absence of an official ruling I would treat them as at least Fine quality. As a base speed 3 weapon, there's no difference between Fine and Exceptional in terms of combat. As a specially crafted item I would not expect that it's possible to add runes to them.

Can the Gauntlet of Immaculate Defense (FiM, p. 20) be used as a weapon (A:RPG p. 242), and if yes, what equipment quality would it have? The same question would apply to the Gauntlets of Force (FiM p. 20) and Crotalus Gauntlet (FiM II, p. 27).

I took a look through both FiM books to see if there was anything on item creation which spells out the quality of item required to make a magic item, but didn't find anything (not surprising as it isn't an option for PCs). I see that the bulk of the magical arms and armour listed in the book are Exceptional or better, but it doesn't seem to be specified for Enchanted Garb.

For Spell runes (Forged in Magic, Vol. II, p.12), the description says that the spell is cast as if the bearer possessed a specified quality-based Passive value for Arcanum skill. Also, the spell uses "the bearer's Charisma as their primary casting attribute." Does the caster add his passive Charisma to the listed Arcanum passive value to get the net passive Arcanum value?