You're getting there.
Yes, for a "basic" check for your cam, you can put it in and check the numbers @ .050".
The reason that you check the cam at .050" on the "upstroke", and then at .050" on the "downstroke". Since the cam lobes are ASSUMED to be symmetrical, these numbers can be used to find the lobe center. The lobe center is just the middle between .050" up and .050" down. Measuring the up and down enables you to be able to use those measurements to find the centerline of the lobe.
I would also check at .001". So for a quick check, I would check .001" up, .050" up, .050" down, and .001" down. Then at max lift, record the measurement at the dial indicator. With this information, then we can figure out the cam specs.
Don't worry about trying to figure out how the different companies measured their camshafts. If you measure them the same way every time, then you can compare them yourself. You set the standard for measuring, as you are doing the measuring. As long as you measure all of the cams the same, then you can compare the info. If you measure them differently each time, then the info won't be able to be compared to the others. You have to measure the same each time with the same method/procedure.
Once you find the valve open and close points, then you can calculate the lobe centers for intake and exhaust valves. then with that info, you can calculate the lobe centers (how far apart the lobe centers are).