dumbledore, chocolate frogs and portrait hopping (book five info included)

[arealin]

No: HPFGUIDX 87278

Hope I'm not repeating anyone's earlier email, I did do a search to 
make sure I'm not.

I recently bought the Unofficial Guide To the HP Mysteries. Don't 
ask me why, I guess I'm either that crazy or that obsessed. It did 
make me think of a couple of things, here's one of them.

In book five we find out that portrayed people are able to hop 
between their portraits. 

1. Can people move between their photographs as well?
2. Does it only work for portraits of dead people or can portraits 
of people who are alive do it as well?
3. If answer to 2 is yes, does that mean someone like Dumbledore can 
enter almost any wizarding family's house through his Chocolate Frog 
Card? 

If all that was possible, that's an even more convenient means of 
communication than owl post or floo fireplaces, isn't it? You just 
hand out chocolate frog cards of a certain person to everyone you 
need to contact quickly and voila!