Staff use with UMD and a similar wand question

[asthyril]

This is 2 somewhat similar questions in that they deal with 2 things I would like to see how they work with a rogue i'm playing in pfs.

1) The first (and easier) question is if you have a spell like ability, can you activate a spell trigger item (eg. staff or wand) as if you had that spell on your spell list?

2) if you use UMD on a staff, what is your caster level? say casting magic missile from a staff, how many missiles would you get? would you need to make another roll to emulate the spellcasting class feature to get your UMD result - 20 as your caster level? if so what happens to the very likely chance it is below 1? 0 missiles based on caster level 0? a bunch of magic missiles blast you in your face?

The reason i am asking is because i have a rogue in pfs that will have at 6th level the major magic talent (shield) and also a staff of minor arcana and go around in robes pretending to be a wizard.

thanks everyone for the help.

[Marthian]

1) Can't find anything on it
2)

Staves wrote:

Staves use the wielder’s ability score and relevant feats to set the DC for saves against their spells. Unlike with other sorts of magic items, the wielder can use his caster level when activating the power of the staff if it’s higher than the caster level of the staff.

[Defraeter]

1) FAQ
Spell-Like Abilities as Spells: Does a creature with a spell-like ability count as having that spell on its spell list for the purpose of activating spell completion or spell trigger items?

No. A spell-like ability is not a spell, having a spell-like ability is not part of a class's spell list, and therefore doesn't give the creature the ability to activate spell completion or spell trigger items.

—Sean K Reynolds, 08/22/11

2)CL is not a class feature (you cannot emulate this with UMD) so you have to use the CL of the object:
wand: min 1 for spell 1, min 3 for for spell 2, etc...
staff: min 8

[mplindustries]

1) No, a spell like ability is not "on your list." It's spell "like" not an actual spell.

2) As Marthian quoted, staves have a caster level you use if you don't have one of your own. The ability to use your own caster level is an optional bonus, and as far as I can tell, there's no way to emulate a specific caster level anyway, as a caster level is not a class feature.