We had a rule check tonight that we couldn't answer. On the Pathfinder wiki I could only find info on natural 20s and 1s in regards to attack rolls and saves in combat.
Do they also apply to skill checks?
A twenty-sided die has a 5% chance, each, of rolling a 1 or a 20. That is a very high chance relative to some of the things you can attempt to do with skills. A 5% chance of automatic failure or automatic success simply is not appropriate to the things that skills are used for.
A particularly good example is the Acrobatics skill, when used to jump. The DC for any given jump you wish to undertake is equal to its distance; if you succeed on the check, you land where you want, but if you fail you fall short. But what if you say “I attempt to jump to the Moon” and then roll a natural 20? If a natural 20 was an automatic success, then you would then jump to the moon. Obviously, that’s not a good thing for the rules to allow.
That’s a pretty extreme example, but for the most part, that’s how skills work: you should not be able to succeed on checks that are greater than 20 + your bonus, nor should you ever fail things that are less than your bonus (because you are thus extremely skilled in that thing, or it is extremely simple, and in either case a 5% chance of failure is just too large).
Yes, but if you ever roll a natural 1 while attempting to activate an item and you fail, then you can't try to activate that item again for 24 hours.
This is a special case that a lot of people read quickly and think is a weird exception where a natural-1 on a skill check automatically fails. Read the sentence carefully: the statement is that you cannot retry if both of the following are true:
You roll a natural-1.
You fail the check.
If your natural-1 is sufficient to meet the DC, you succeed, and are not limited in using the item in the future (at least as normal for that item; if it’s out of charges or whatever, that would stop you). You only have a problem if your natural-1 is insufficient to meet the DC.
Note that scroll mishaps occur in the same circumstance (natural-1 that fails).