hey jim,
well, im just a beginner too and there might be a better way to do this, but here is what i would do:
i would put in a said command like
(if(Said('open/door'))
= button Print("which one would you like to open?"
#title "Which?"
#button "The car door" 1
#button "The house door" 0
)
(...)
)
and set up the two buttons with their appropriate endings.
as for your other question, i dont know but i bet that it has something to do with which of the two the computer can do faster...but again, i leave that to someone smarter than me, but dont worry cuz there are plenty of them out there

doan