Answer 1

I didn´t think it´s possible, but...
http://bulbapedia.bulbagarden.net/wiki/Volcanic_Pit_%28friend_area%29
It has recruit rate of -10%, so you need A LOT of luck

Answer 2

http://pokemondb.net/pokebase/10712/what-legendaries-recruit-pokemon-mystery-dungeon-blue-rescue Already asked.

Answer 3

Regardless of what you do the chances will be miserable. BUT if you bring 2 level 100s have the leader hold the Friendship(?) band you should have a tiny chance of it.