Well ill be honest i dunno what changed since i played but if u have enough mana (which i did so u def should
) u can keep spamming AB 4x with high crit it WILL proc the thingy-blingy (aww it was so long ago i cant recall the names
)
I dont really know about the lenght of the new fights but i had no mana problem with the beasts of northrend encounter which is fairly long with no possible breaks but u have to keep in mind that u have gems and your evo's cd is kinda short. If u dont wait with the gem and use it as soon u can, ull end up with more then enough mana. (also dont be shy to make a 2nd gem from your evo if u used all 3 charges)
gl in there
remember u r a glasscannon
oh and btw with enough mana and crit u wont even need the last tier arcane stuff some ubermage told me back when i was respeccing