I agree with Sam1911.
This isn't a finished cabinet that's going to be on display in the livingroom or something. It's a durable workbench.
Definately double up on the countertop. I like the thought of Birch for the countertop because it's got a nice, light color and a really good, cabinet level, face. When doubling up, you don't have to use Birch for the bottom layer, though...pretty much a waste of money, in fact. Use Birch for the top only.
This will give you a smooth, light colored counter top on the bench. I like the idea of a light colored counter top because it's easier to find stuff laid out on it compared to darker colors. And it's ALWAYS nice to have a work surface that enhances the lighting of the workspace. Better on the eyes and better on the lighting requirements.
If you want the countertop to look like a solid piece of wood, you can face the edges with a strip of wood, trimmed to fit, and sanded flush with the countertop. If you'd like to have something to prevent tools and such from rolling off the countertop, trim the strips of wood to give you about a 1/4 inch lip all around the top.
If you stain it, stain it light. I don't like glossy finishes on such surfaces, because they can be annoying as work surfaces go. I would finish it with satin finish polueurathane. In fact, I'd probably go with something like a MinWax stain and polyeurathane finish, which combines the stain and finish in one produce. Get a light colored stain/finish in a small can and try it out on a scrap piece of plywood left over and see if you like it. If so, then buy enough of that in a larger can to do the job.
It'll probably take three coats to properly finish it and make it look decent. Take your time with each coat and be neat about it. The first coat, minutes after you put it on, will likely seem like it didn't do anything, finish-wise, because the wood will really suck up that first coat.
Lightly sand smooth after each coat is thoroughly dried before you put the next coat on. The second coat will look a lot better because the first will have sealed the wood pretty good. The third will look even better. For a workbench, I probably wouldn't go beyond that, though you can do as you see fit of course.
Since it's a workbench, I wouldn't go any further than that. It'll look decent and the finish will have sealed the wood to help protect it from spills and what-not.
With a double layer of plywood, the top will be plenty sturdy enough to mount your reloading equipment.
As for the durability of hardwood for the countertop...you're planning on using this as a reloading bench, not somthing to hammer on. If you're looking for a surface to hammer on, that's easy enough to accomplish with this: Get yourself a piece of steel plate cut to size to serve as such a surface and simply lay it on one end of the countertop. You could even make it brass if you want it to be non-sparking.
If I might make an additional suggestion here, just based on my own thoughts:
I'd consider making the countertop stick out an additional 4 to 6 inches to give you a little bit more of an overhang. It's easy enough to do, and will be plenty sturdy for a doubled layer of 3/4 inch plywood, plus extending the supports out as well. This will give you the ability to scoot right up to the countertop on your stool/bench without wacking your shins on the shelf below. No more than 6 inches, though, and be sure to support this with framing modifications because you'll want this portion to be able to mount your press and such without flexing. Maybe make the front framing piece 2X6 for extra durability, as the major load bearing beam for the press.
)
