These are my considerations about the feats you mentioned:
Silence of the Dead
You want all the -hate you can get, especially in certain phases, like Toth 1st and 3rd. Of course, if you have t5/t6 tanks, you won't need it that much, but I don't think many of them are still going to t3.
Deathly resilience
310 protection for 3 points is good.
Unholy fortitude
Not useful at all. Pets should not take damage, and even when they do (Louhi) the debuff will kill them anyway.
Netherworld Deception
The -hate part seems to be bugged. The utility of this feat is that it reduces pet size, and lets them sneak in when the boss is crowded, and they would have no space otherwise.
Night of Harvester
The good part is that it removes the mana cost of lifestrike and it makes the spell restore mana. And there are not many other useful feats anyway.
Master of the dead
Must have to summon the 4 points pets on Hator-ka.
Flash freeze & Frost blast
Not useful for dps, but for cc, on trash, Keeper 1st part and Toth. Especially Flash freeze was very useful as interrupt. Of course now it's not needed anymore for that, but still it can still save the life of a dps, if he get's aggro.
Iceshards
You want to splash the snakes and the demons on Toth.
Plague swarm
Never fount it to be useful. I'd rather spend points in Infestation.