For a stuck slave, if you select an area including the dead one and a live one you can drag both... even to the butcher.
You have to accept losing one to get rid of the corpse(s), but that did clear it for me.
If you click into a room there is a section to select a slave in teh room, which focuses the camera and lets you rotate it (until you right click).
Goblin upgrades are all done pretty much the same way. If you have a slave feeding/caring for a goblin, they have a small chance to upgrade on growth (5%ish). I think a high elf perk can add a few percent there, but not much.
Upgrade a 2nd tier kid for a chance at the third tier (and I cannot get past that).
Note: You can save/load as that check is done when the baby grows to adulthood. But for mix parents a save/load randomizes the race of kids (which confused me a few times).