will this get rid of feedback for the most part? and how else will it affect my pickup
It'll definitely help to prevent microphonic feedback. However, if you play really close to your amp, you'd probably still get feedback. Most pickups are already wax-potted, though.
It won't get rid of feedback, that's normal. Odds are your pickup is already potted and trying to pot it could ruin the pickup.
What dave said - potting will get rid of michophonic feedback, but not the feedback you're probably talking about. That's a grounding problem, a whole different kettle of fish. I'm assuming you have a Strat-like guitar, so read this
Sheilding will not get rid of feedback either.
^ I've heard lots of people referring to grounding issues as 'feedback' and assumed he was talking about this.
If it was to do with grounding it would be more of a hum. I'm pretty sure he's talking about actual feedback.