you would loose about 1 to 2 cups of 90weight gear oil, and less if you have the wheel that you are removing higher than the other wheel. I stuff a rag in the axle hole to prevent much more oil from spilling while the axle is out.
Yes, I saw the part with; "1/4"-1/2" of easy play and then locks up hard". I expect this to be the shoes moving on the backing plate, twisting with the drum they are stuck onto, but only as far as they can before the hardware catches.
I work for a company that buys "off lease" trucks from other dealers, and we often see trucks that the shoes have stuck to the drum from rust after a few months sitting. they mostly move a little bit like you say.