For #4, no, it was the same in KeeperFX 0.4.6. I was just wondering if it had been fixed in this release, but after getting to level 4 can see that this behavior is still there. But yeah, it doesnt look like actually moving gold around, more like distributing gold to various different stack which makes them very less efficient at mining. This is most likely caused by multiple stacks not being at it's cap, but the imp has too much gold to distribute in 1 stack so it splits it in many of the existing stacks. A possible solution to this would be that when an imp drops gold into the storage room, it automatically splits it, but that would most likely be core-game functions, not a setting.
I'll just get used to disabling gems or manually dropping imps later in the match when I start capping my storage room.
Asides from that everything is great so far

looking forward to later levels.