can the Aasimar FCB apply to the Undead Servitude Revelation, boosting my command DC?
I believe that the FCB gives you +1/2 levels toward your oracle level for the effects of one revelation.
Command undead Feat is based off of Caster Level.
do these bonus Oracle levels confer imaginary CL's for the purpose of the revelation.
I would say that if my oracle level goes up, my oracle CL goes up...
but only regarding the Command Undead Feat.
It won't affect it. The Oracle Favored Class Bonus for Aasimar is:
Oracle: Add +1/2 to the oracle's level for the purpose of determining the effects of one revelation.
This means you look at the revelation and any level-dependent effects increase by 1 for each 2 times you take the favored class bonus; or effects that change at a specific level change earlier. 2 examples:
1) Armor of Bones from the bones mystery you were looking at: "You can conjure armor made of bones that grants you a +4 armor bonus. At 7th level, and every four levels thereafter, this bonus increases by +2." If you take this at level 1 and put your FCB into this revelation, then at level 5 you count as being level 7.5 (so at level 5 you get +6 armor bonus); at 8 you count as 12 (so +8) and at 10 you count as 15 (so +10).2) An oracle of life with the Channel Energy revelation ("using your oracle level as your effective cleric level") at level 2 with 2 FCB's counts a oracle level 3 (effective cleric level 3) and gets to channel 2d6 instead of 1d6. Let's say at level 3 he takes the Life Link revelation ("You may have one bond active per oracle level.") and puts his FCB there for 3-4. At level 4 he counts as level 5 for both revelations, so he channels 3d6 (as a level 5 cleric instead of 4) and can link with up to 5 creatures.
The Undead Servitude revelation says:
You gain Command Undead as a bonus feat. You can channel negative energy a number of times per day equal to 3 + your Charisma modifier, but only to use Command Undead. You can take other feats to add to this ability, such as Improved Channeling, but not feats that alter this ability, such as Alignment Channel.
Unfortunately, there are no "level dependent" effects in the revelation; it just grants you the Command Undead feat. (The feat has level dependent effects built into it, but the favored class bonus doesn't apply here by RAW).
In a home game you would not be _way_ out there to ask your GM to let ot count; I personally probably would (though I would do some math first--like "how powerful is this at level 10 or so when you count as level 15..." and I'd ask myself as GM how many powerful undead I'm planning to have--it's not really interesting if the "big bad guy" just suddenly becomes a PC's slave halfway through the game because you count as level 15 and he's got 15 HD or whatever).