Dispel magic questions

[Epinephrine]

I know I could ask in the RAW thread, but I don't want just RAW, I also want to know how people actually play it.

a) spell-like abilities are affected by dispel magic; are they treated as a separate set of effects or the same as spells?

e.g. Warlock has an invocation up (say, Fell Flight?) as well as a magical buff (Mage Armour) and comes under the effect of an area dispel. Dispel magic may remove one spell in effect on the warlock - does it check spell-like abilities in their own category, potentially costing the warlock both his Mage Armour and his Fell Flight, or is the spell-like ability counted as a spell in effect, and thus he's only at risk of losing one of them? How do you determine order of dispelling spells if they are at the same level? Randomly?

b) Magic items are not affected by an area dispel, but "For each object within the area that is the target of one or more spells, you make dispel checks as with creatures." - if a magic item (like a +1 sword) is under the effect of a spell (umm, Frost Weapon, for example), is the Frost Weapon spell affected in an area dispel, as it is a spell on an object? My interpretation would be that an area dispel doesn't affect a magic weapon's base abilities, but I'm having trouble with the idea that the magic item would somehow protect the enchantment on it.
b) would seem to matter a lot, as one might cast a Silence spell on a magic item and thus the spell becomes immune to area dispels.

[Douglas]

a) SLAs do not get their own category for dispelling. The area dispel would remove no more than one of the two effects. When caster level is the same for both, I'd determine randomly which to check first. RAW doesn't specify an order in that case.

b) The item itself is unaffected, any spells on it are. In your example, the Frost Weapon spell would be subject to a dispel check. I think this is correct RAW too, but it's definitely how I play it.

[Keld Denar]

Douglas has it right on both accounts. Another example of b) would be an Invisibility spell cast on an object. And the Silence cast on a magic weapon would be just as vulnerable to area dispel as a Silence cast on a non magical rock or copper piece. The difference is that the enhancement bonus of the magical sword would be protected, while the rock itself has no inherant magical properties to be protected, just the Silence spell. Therefore, there would be no difference.