A microbevel provides a way around the need to hone the entire surface of the main bevel each time you sharpen. Honing with a fine grit stone removes material slowly; the larger the area the slower.
The down side is that each time you hone the microbevel it grows in size. Being a steeper angle, this will eventually change the geometry of the cutting edge to the point that you'll have to grind it away and restore the proper angle. I try to minimize grinding, especially at the thin leading edge where heat builds quickly to the point that you'll ruin the steel's temper.
An alternative that also reduces the area to be honed is called hollow-grinding. Instead of shooting for a uniform, flat bevel, very carefully grind out material above the cutting edge, creating a depression, or hollow. When honing, the forward and trailing edges of the bevel will still ride the stone and create the proper angle, while polishing a minimal amount of surface area.
I don't think a swan-neck chisel will find much use in timberframing, where the mortices are usually large enough to turn a framing chisel bevel-side down to clear the bottom. Short, deep mortices, such as those for the old-fashioned locksets cut into the edges of doors, might require a swan-neck.
As Jim says, the outside of a corner chisel is the easy part. You can do some shaping inside with a file, but they don't leave a polished surface and cutting edge. Have you ever noticed that a lot of antique corner chisels have a long point at the corner? That's the result of honing with a stone, which eventually gets rounded over on the edge, and doesn't take as much material out of the inside corner. The further you hone back the wings, and the more your stone gets rounded over, the more pronounced the point. A diamond plate, which won't wear away and round over, can be used for all but the finest polishing on the inside corner.
Most chisel sharpening is done with the stone on a bench, and the chisel held at the proper angle.
I've found it better to clamp down the corner chisel to sharpen the inside edges, and move the stone. I can keep track of where I am better that way. I use the same technique with slicks, axes, and other tools where it's awkward to hold the tool properly or to see what's going on.