Dealing post premiere effects

Hi all, i just have a few small questions about after effects that i was hoping someone can help me with (let me know if i should not be in the basics section). Im very experienced with premiere pro 3, but a novice when it comes to after effects (im using 7.0 so i can take advantage of the magic bullet series).
Im coming close to finishing the edit of my major work project, by that I mean ive got it more or less 100% completed except for an effect i was hoping to do in after effects. (Let me know if im on the right track here :)) I export my final product from premiere at the highest quality setting and then import the avi into AE to begin work.
The first thing i want to do is de-interlace the footage, but i wont waste your time with that as there are millions of tutorials out there for doing that. I figure then ill do a max quality render of the de-interlaced project and import it back in to put some effects.
The biggest effect i have to do is about 4min worth of turning one actor from color, into black and white. The only way i have seen how to do this is to double the layer, apply the tint effect to the top one, then use the pen tool to make the net around him. I then move the keyframes forward slowly but surely adjusting the net as i go, and keeping him black and white.
Does that sound like the easiest way of doing what i want to do? It is going to take ages, but from what i can tell its my only option.
The main problem i can foresee is when i have a fade into a different shot, and my black and white actor is present momentarily in both. Can i make 2 pen tool selection "nets" at the same time? and is it possible to fade them in and out so im not left with a black and white blotch where the actor has faded?
I hope that makes sense, ideally i would apply the effect in premiere pro, that way the divide between shots would be maintained, and the fades and stuff wouldnt be a problem. Like i said, any suggestions of a better method would be much appreciated.
Sorry the post was so long, its a pain to explain
Cheers
Dave.