ALL rifle barrels come drilled and tapped for a scope rail and not a lot come with sights, most are scope only. Don't worry about the front of the scope base, it works just fine, just as it does on the TC Encore which is unsupported the same way on the front ~1".

Some folks feel the need to epoxy bed it including the unsupported end, but I've never done it or felt it needed to be be bedded or supported. The Ultra rail has a set screw in it, but it's not designed to touch the barrel, just provide support in case the a large scope mounted on the front of the rail is bumped, how to adjust it is mentioned in the FAQs also.
How your scope fits in relationship to the hammer depends on the scope, there are a myriad of scopes and designs, positioning and the size of the power ring/ocular bell will determine ring height, you won't know until you try to mount it.
Take a look at the link titled "Let's See some Handis" in the FAQs, lots of scope mounted H&Rs to look at.

Tim