this is my first double tourny... scary stuffs

I'm test playing soon with someone who plays VC (mainly around a horde of grave guard with a vampire hero, direwolves for caster hunting... and i believe he said vargulfs but he might just of been spitting ideas)

my list is currently

HoTz
-Mastery of Sorcery (life, if he takes vargulfs, doesn't seem worth if hes not as there's not many things that can benefit from the lore bonus)
-Winged Horror (he needs to stay alive)

15 bloodletters
-Champion
-Standard

5 Flamers (his entire core is dire wolves... seems daft to invest in more chaff)

211 points left over, now the question is... 6 flesh hounds... or 2 units of 3 screamers... i think they might do well at low points, but the fragility of them is still so worrying...

anyway as its my first doubles... any tips... I've literally never played a doubles game before... input is greatly appreciated. I'm kinda clueless in this area.

oh can someone with doubles experience answer me a question

If Skulltaker joins a unit of Graveguard, and the spell hellish vigour is cast on the unit, does skulltaker benefit because hes in an undead unit, or is he excluded because hes not undead?

we were brain storming around the idea of him being the caster in the army, (because he can take a lord) but if only his units can be buffed, it will be nerfing our army as a whole