The demon crit, giving spell power will not stack with Totem of Wrath.
If your warlock is at 2800 spell power, these buffs are equal.
Under 2800, and the Totem is better; over 2800 and the warlock buff is better.

If you're going Demon, don't waste your points on those five talents.
Take your pick...
Either spend the 5 pts elsewhere in the tree making your demon stronger.
Or forgo Metamorphosis and those 5 pts, going deeper in Affliction or Destruction.

Affliction will get you... an instant cast fear.
You'll probably go with the Felhound for spell lock and decurses.
You'll go with a castsequence reset=target, which includes UA, Agony or CoElements, Corruption, Haunt, Immolate.
People detest warlocks because they're killing soemthing else and suddenly see 4 or 5 dots on them.
Then they die.

Destruction will get you nukes, similar to the shammy style of play.
You'll have the AoE stun, which is a mouse target move so either the lock is the main screen or you'll need a decent mouse broadcasting option.
The imp will be the pet, for some Fire Resist, a damage shield and hit point boost.

Demonology gets you a sick pet.
The pet will charge (intercept stun).
Soul Link transfers some of the damage you take to the pet (although this is early enough that either other spec can grab this for pvp's).
You can go 50/21 or 51/20 (Demo then your second spec), either Affliction or Destruction.
With talents, either other tree is a valid choice for your dps.
You'll lack a bit of the talents to make spells better, but the demon will get a ton of raw spell power.
Your Seed of Corruption spell will be sick.
I raided T5/T6 level on a Demo/Dest warlock, had a blast.