ok, firstly, i HATE spiders! so why am i even considering this???

heres what i dont understand:

i want to take a picture of a bedroom (with wardrobes, drawers slightly pulled out etc) and i want to use that as a still (non-moving) background plate. then i want to have all these hundreds of spiders emerge from beneath the door of the room, from inside the drawers, cracks in the walls, everywhere! what i dont get is how i can do this?

i know i ahve to model and animate a referance spider (no problem) then i instance it to particles, but how do i make the partcles act like theyre climbing along lots of different surfaces? i cant use path animations cos theres more than one spider and theyre coming from all directions in a random manner

any help would be appreciated