Frost rotation question

I've read the EJ on Frost rotation and I get the concept below. But I have a couple questions. When your high priority shots are on cooldown (DF, BF, pet freeze) should you weave IL after each FB? It's an instant cast and you can weave FB/IL -> FB/IL -> FB/IL until higher priority shots are off CD? If not, why?

My next question is that when you have a mob in DF is it better to spam IL or do FBx2 and an IL if you can get it in there?

Thanks

Frost priority list

Frostfire Orb, if cooldown is up.
Deep Freeze, if cooldown is up and Fingers of Frost is active.
Frostfire Bolt, if Brain Freeze is active and Fingers of Frost is active.
Ice Lance if Finger of Frost is active.
Freeze, if cooldown is up, Deep Freeze cooldown is up, and Finger of Frost is not active.
Frostbolt.
1. You don't add an Ice Lance after your Frostbolt, you queue the next Frostbolt.
2. I would just spam Ice Lance on a mob in Deep Freeze.
3. You always save a FoF for Brain Freeze procs.
4. I would use Frostfire Orb when I'm FoF starved. (Not entirely sure about this one as I don't have it yet.)