I play quite a bit of Vik (with VonSchill) and here are my suggestions.
Since you have 3 guys that can use soul stones you should try to get as close to max as able. They are essential to keeping Vik alive and making sure she always wins combat. Also Von will rock alot of models with a stoned pistol shot.
Vik's avatar is really bad. I think she is a much more powerful model as two masters. Also if you like to control your models the avatar totally cuddles that.
You should run a convict gunslinger. He is the best model in the game for his points. At 5 points he is the steal of the decade.
Also Ronin are great for your list. They are great models, cheap, kill stuff, super tricky with run through and if you need more stones they are more then happy to commit seppeku. Not to mention can creat another Vik if needed.
Alot of people like the librarian but I don't really care for models that are fragile and really don't do much by themselves. For her points you could take Taylor if construct killing or high willpower are needed (not to mention she is a tank).
He is a example of my standard list:
Vik's
Student of Conflict (3)
Von Schill (9)
2 Ronin (2x5)
Convict Gunslinger (5)
8 soul stone pool
(if you think Taylor would be needed drop a ronin and student)
I have used this list to great effect. The key to Vik is using the combat buff then movement pulls and switch. Also if they cluster together use your whirlwind to murder them all. You will be outnumbered most of the time but, with so many stones 3 of your models are very hard to kill/able to alpha strike.
Just my thoughts