Yes, so long as they comply with the national regulating body's rules on Rugby boots. I don't know where you're from, but my national body is the IRFU. This is not a link to their site, but nonetheless provides useful information about what is and isn't legal o the rugby pitch
Yes however there not practical and aren't designed to kick balls.
Its because they have studs that can aid grip in the grass and muddy conditions that the game is played in
No you don't need to wear football boots, you could wear running shoes.
Rugby players wear boots.
Le Coq Sportiff Rugby Boots
I wear the same boots that c.ronaldo wears so I wear mercurials because c.ronaldo is the football player I admier and mercurial boots are the only type of boots I would ever wear.
Australian footballers wear much the same as soccer and rugby players: team guernseys, shorts, club socks and studded football boots.
Well i would prefer cleats over boots...