husqvarna...
not a pilot myself, but from experience with flight sims;
'Heavy' just means that the aircraft is large, and heavy, which the controller uses to plan spacings, and note different speeds/altitude requirements??? (might be wrong there).
Larger aircraft disrupt the air around them, so a smaller aircraft following would get a rough ride. By telling ATC you're heavy they can leave a larger gap between you and the next plane.
And V1 is a stage you go through on the runway during takeoff if I'm correct. I think its to do with speed, but again, lack of real-life experience means I don't know. lets hope a pro replies
