I have had my Judge since August 2007, Matt Stainless, 6.5" barrel.
even with a couple flyers that are not off the target, I can consistently put all rounds on a 5" sticky target on cardboard. I could not until I bought that Hogue grip, because it tore up my finger under the trigger guard after 5 rounds. I think you will love it after you fire with those grips.
Holsters, they are starting to produce more and more for the Judge! I wondered if they ever really would for a few months. I went looking for other stuff this week, and discovered that not only are they coming out with the newest version that will fire the 3" magnum 410, there are now at least three barrel lengths, 3" 4", and 6.5". I bet they all come out in the 3" size cylinder too. Three finishes, Blue, Stainless (shiny), and Matt Stainless, so gee they must be going to keep making them for a while.
Ammo, well I have used just about the full variety available, 200gr, regular and cowboy load FMJ, 225 gr Blazer JHP & FMY, and 250 gr JHP, in the 45 colt. 410's to find a lot of variety you have to look around a bit. Most places do not even stock the 00 or 000 but #4 thru #9 are readily available.
Oh about a laser, I did get a very cheap, $12 rifle laser set, If you mount it above the barrel on my 6.5", you can see the regular sights, or shoot it with the laser. Not sure if you could attach to the trigger guard, but as they are universal, you probably could.
I only did it for a test, and found that I was hitting POA, at 45 feet. But with the cheap red laser, unless it was very cloudy or dark out I could not see the laser very well beyond about 30 ft.