* You may have the amperage a bit too low.
* You may have let the rod get too close to the parent metal (arc length too short).
1) They certainly do. If they're wet enough, you may not be able to use them at all.
2) Dampness can cause the coating to fall off in chunks or unevenly & cause "finger-nailing", where part of the coating sticks out beyond the rod end, during welding.
3) Missing chunks of coating will make the rod stick a lot, plus your results may not be satisfactory.
4) Keep your rods in the house if possible or in a heated storage outside.
5) You can also get away with keeping your rods in a SEALED container to keep out moisture.
1) YES, & faster than you might think.
2) I wore short gloves once & got my arms burned.
3) ANY uncovered skin that's near enough to the direct welding rays will be susceptible.
4) Helpers that are holding things in place for you should be covered too, when exposed more than a few seconds.