Just test the mA ranges. What is the highest reasonably accurate voltage you have? 50V across a 10k resistor is 5mA, and 10k is high enough that the burden voltage offset will not be too high. You can even measure it and compensate for it in your calculations. If you don't have such a high voltage you can use a lower one, you'll just need to measure the current shunt resistor and compensate for it. (You can use the meter to measure its own shunt. I see it uses shared jacks, so you can't do the "bridge ohms and amps" trick, but you can slide the case open and probe it. Just don't connect ground.) Calculate the current, don't measure it. Screw the A ranges, who the hell needs precision above 100mA anyway....? 
The spacing looks proper to me.... Of course, I can't estimate small distances in inches for shit, but it does look like about 20mm...
I'm not sure what you define reasonably accurate. I have a variac and some 600v diodes and a 600v transformer so tecnhically I can get some pretty high VDC but I'm not sure if it has the accuracy you'd want.
Other than that I have a hacked 7805 that can output up to 15v, that's about it. I'm nervous about all of this resistor business, I don't really ever go about using them for anything precise or with current.
And as for your last statement of that paragraph, *raises hand* "uhh......I.........I.....do..." lol
Most of the current ranges I ever measure are up in the amps, though now if I have the capability for mA, I guess I'll start using it more often.
Hmm, I'm the opposite, can't estimate meteric even a quarter as precise as I can in imperial, and even that I'm not too good with.