Animatronic security system

I will be building an animatronic portable security
system for my motorcycle. I will have a detachable talking skull that will have my voice to warn people that get within 3 feet of my motorcycle.
I do have experience with building talking characters
but only with fright ideas controllers.
I was thinking of using a Mini Maestro to play a motion sensor triggered script sequence
for the 3 servo motors in the talking skull.
I was thinking of connecting a Spark Fun Mp3 player
for my triggered audio. I would also like to have a blue tooth message or signal sent to my iphone
at the same time my skull starts to talk.
I mostly need help with recommended shopping list.
I am hoping I can connect all components to a board.
I will start with my 12v DC motorcycle battery.
I will also have the talking skull and a small mounted
speaker. Can someone help me with component ideas. What sort of motion sensor or sensors might
work well. I was thinking PIR. What about a blue tooth device that would tie in?
Would it make more sense to start with an arduino
and stack an MP3 shield?
Please advise me.