[911 Rod]

I'd take the muffler off the car. Can't do a nice job otherwise.
Cut off wheel for sure, but I'd get the shop to do the cutting and welding. It will take them 2 minutes and then there will be no excuses if they botch the job.

I hope you have a shop that you have used before and can trust. I went into a Speedy last week to get a slip joint on my Tundra exhaust re-welded and they wanted $369 + tax. I could not get out of there fast enough!