Will you be shooting from a rest or offhand. If you'll be shooting from a rest you can probably see some advantage with a scope capable of magnification up to 8X. If you'll be shooting offhand IMO 4X will be the maximum magnification that will be "uesable".
Personally, as a long time Nikon camera user I've always been impressed with Nikon optics. I have a Nikon Monarch 2x20 EER that I'll use occasionally on my revolvers and it's well made, has fantastic clarity, and has held zero without fault. However I find the magnification to be a bit limiting beyond 50 yards when shooting for precision. However, for shooting silohuette it may be just the ticket, unless you're shooting a light caliber shot placement isn't that critical. Currently the cost for the 2x20 seems to be running in the 160 dollar range, which while not cheap is IMO a good value for the money spent.
More recently I've been looking into the Nikon Encore 2.5-8x28 EER. Downside to this model is that IMO 8X is useless for shooting offhand, only a robot could hold a scope with this much power steady at 8X at arms length, for us mortals the shake would just produce a blur. It's also a distinctly larger and heavier scope for handgun use, a product of that high magnification. Ideally I'd like to see a variable power in the 2-4X range, however people tend to be attracted by big numbers even when they are not practical. Cost for the 2.5-8X28 EER is currently 310 bucks locally.
As for a mount, your really need to finalize on your scope choice before purchasing a mount. One tip I can provide you is to avoid the Burris mounts, I purchased what I and my dealer though was a Weaver mount and only found out later it's a propriatary mount that is NOT wide enough for a Weaver rail, snapped a mount like a dry twig trying to force it on my rail. Other than that I can't provide a lot of guidance on a mount, there are just so many good ones out there. Mine is a garden variety no name mount made by a local machine shop and sold in a small gun shop down the street from work.
