A few times now I've found over 30,000 ore in mining stations or their debris field. If you happen to hit salvage all and not notice, the extra cargo will eat up all your supplies in a few seconds.
Same here, but I'm usually careful to make sure I have the cargo space (exception being supplies of course, no point chucking them might as well use them at an increased rate). I wonder if there should be a hard cap on the number of cargo you can take over the limit to avoid this sort of thing happening.
Also, how much would it cost to run a fleet capable of carrying 30,000 ore? 15 Atlas's, 150 monthly supply, 90 fuel/light year...hmmm maybe it would turn a profit, but if you can afford that fleet to begin with, I'm not sure if it would even be that lucrative, though that is merely my uninformed opinion (need to dig further into the math to see whether it makes sense or not).