that is the question mate........that is the question*sighs*

but u know the wizarding photographs/portraits thingy is the number one on the 'confused abt harry potter' list. honestly........anyone i speak to(i just realized.....I HAVE NO LIFE!!) are wholly confused abt it
ive always felt that jk has never maintained an actual standard abt it u know? like she's set the basic 'they move' thing but hasnt developed it further- and has used it as when she needs it. like if she just needs us to see the photo we see them waving and smiling( the weasleys in poa) and when she needs it to talk it talks like mrs.black
but then to satisfy myself i thought u know the whole theory abt since photography is an electronic experience and therefore it is less fulfilling but a portrait painter has to sit with u for ages and for days together and it is done by the human hand so somehow it becomes more personal
like the painter somehow gets ur personality cuz she/he spends more time with u and it subconsciously affects the way he paints you(like ud know if the subject had been the painter's loved one)
and ive noticed that jk takes a lot of the metaphorical sayings and makes it real- gives it an actual physical shape and form(dementors....)
so this is perhaps her way of expressing the belief that a photograph doesnt capture ur true essence whereas a portrait does
therefore wizarding portraits have ur personality whereas a wizarding photo doesnt?
frankly i dunno mate.............im just thinking out loud
and to answer ur other question, it might have some intelligence- some mental capacity u know but i dont think if harry carried a portrait of dumbledore to his exams, dd would tell him all the answers(ignoring of course the fact that dd wouldnt unfairly help students like that)