Answer:
1) Some people believe that we are each assigned a personal guardian angel. This being apparently takes of us and acts as our benefactor. If this is true then mine will get the sack when i get to heaven :-)
2) They act as Gods messangers and basically keep an eye on us.
3) The Bible does say that we would entertain 'angels unawares'. So basically they are just hanging around and you might meet one.
All in all, they a little mysterious. Nobody really understands how they impact us and personally that's probably for the best :-)