For the most part, yes. But the wormhole physics I established for a connection to the End doesn't only apply to paths between the two planets; there can be portals connecting the Minecraft's surface to the nether, or one End island to the next.
Actually no, but there isn't a single large boom, there are millions of small ones that make that familiar 'zwoop' sound. The ionizing displacement temporarily de-unifies endermen as a singular entity, and each cell is technically pulled towards its own electron cluster independent of its neighbors, though they maintain their arrangement through simple interlocking segments of their cell walls. So an enderman's body doesn't move all at once, rather, it is stretched into its component particles along its pathway and snaps back together at the end. (This definitely wouldn't work for organisms with our or similar cell structure)
I actually hadn't given a thought to elytra, but now that you've brought it up, I might include them as a new type of organism. Thanks :)
That's pretty much my plan for when the update drops. Basically, hoglins are an offshoot of the basic pig family that migrated into the Nether cave networks around the same time as zombie pigmen, and piglins branched off from the latter as they selected for intelligence over power.