I believe the link above talks about cutting and splicing your existing 'plug' for the mirrors. Transfer it over onto the new mirror and it'll be all good to go.
Yep...drilling the holes bigger and using washers on the backside, then the nut and they are secured.
I've got no pics of the drilled out doors, but I want to say it was 7/8" that I drilled the holes out to? idk.