A curve in the back of a broad axe is a good thing, and I think that can also be said for a slick, although to much less of a degree. Your framing chisels, should be fairly flat, but I don't think one needs to be as anal as a cabinet maker.
The sandpaper on glass/granite works well. It has a cheap initial investment compared and one can make a larger sharpening or flattening surface then with stones.
When it comes to plane blades I am a fan of David Charlesworth's "ruler trick". You need a decent back to start out, but can save one a lot of time as it elevates the blade to a slight angle so one is only working the metal very close to the edge, basically creating a slight back-bevel. This does not hurt the performance of the plane because the blade is already pitched at a higher degree.