| RulesEsquire |
Most of your bonuses would stack... but only in very specific situations. Imitating a human you have met with a disguise of +56 is very powerful... But that is not till level 7, at which there are a variety of...
I apologize, here is how I believe the math would break down:
To simply appear as a human:
+10 racial bonus to appear human (Kitsune)
+10 untyped bonus (alter-self)
+20 circumstance bonus seamless shapeshifter
+10 untyped bonus - vocal alteration
+10 Disguise skill (assuming 1d3x10 minutes)
+2 Disguise kit
______________
+62
^basically, without magic, no one would know you are not a human...
To appear as a specific human:
+10 untyped bonus - vocal alteration
+10 circumstance - realistic likeness
+10 disguise skill (assuming 1d3x10) minutes
+2 disguise kit
________________
+32 to appear as a specific human (polymorph and such are just to assume a human shape, not look like a specific individual). While that might feel "unfair", that is the problem with "rules-as-written".
You might be able to convince a DM otherwise, but, I believe that by RAW, that is how it would break down. Note that the other bonuses you mentioned all specifically mentioned shape (or form). Polymorph and similar disguises are just to appear as that shape/form... not as an individual. You can probably convince a DM (or many DMs) that they should work that way... but by the letter of the law, it appears they do not.
P.S. I can break down the bonuses for non-human disguises as well, if you like.