Just one
There are 26 legendary Pokemon in Pokemon black/white version.
9 excluding reshiram and future event Pokemon
in unova, about 7 legandary pokemon. in total, about 28.
There is no legendary Pokemon in Undella Bay.
There are many legendary POKEMON in black and white ZEKROM and REGISAM
there is no "white" legendary in pokemon white. its black ( and called zecrom) and in the top floor of N's castle and then after u VS N
Zekrom.
White Kyurem
It's not possible, legendary Pokemon cant be bred.
No.
no
on pokemon black version u get the legendary pokemon reshiram!(sry if its spelt wrong) and in white u get zekrom! u get the legendary after u defet the pokemon ledge.