2 questions about killing trash as a SPriest

[nosoup4crr]

1) how large does the trash pack need to be to make mind sear your first choice? 3? 4?
2) when it doesn't make sense to use mind sear, what rotation do you switch to on small numbers of mobs with 60k-130k life? Which DoTs, if any, are still worth it?

[Lackluster]

1) 4
2) Put VT on everything then singletarget rotation on 1