Media Blasting Questions

I'm finally finished with as much metal work as I can do before sending the car out for media blast. The plan is to deliver the car to them tomorrow morning.

A local shop is willing to blast my car for $800 using Copper Slag. Anyone heard of this media? Is it a good choice?

I think $800 is a good price. The job includes the body, doors, fenders, hood and trunk lid. The car is fully apart and mounted on a rotisserie. I have already removed all the undercoating, seam sealer and grease.

I'm also looking for advice on the hood and trunk hinges. They're still on the car. Should I leave them on for media blast or take them off and blast them separately? Are they hard to get off? If I take them off, when do I put them back on? After primer? After paint?

Finally there is some kind of sealer in the rain gutters. The car is a convertible so the only gutters are in the A pillars and they're wrapped in stainless/chrome trim. There are some cracks between the metal and whatever sealer is in the gutters. I'm not sure if I should worry about this. Do I remove all the sealer and start over, or should I leave it alone?