Wow I actually love this idea. There could be some common symbol in the crests to denote what kind of open source license they follow (GNU, MIT, etc), affiliation with other software, all sorts of cool stuff.
Yes and no. The truth is that most of the community responsible for keeping Minecraft relevant are on Java. If they kill Java, they also kill Fabric, Spigot, Paper, all the modpacks and such.
Java is the marketing department, Bedrock is the sales department. Mojang needs to keep Java just functional enough for the community to do the marketing for them.
A portal that faces downwards into another portal is effectively a perpetual motion machine. Drop a ferromagnetic object into the loop and wrap some wires around the loop, now you have an infinite electric generator.
All motion is relative. To understand how the people will move, we need to look at them relative to the portal. If the trolly is moving at 5 m/s relative to the ground, then the people are moving at 1 m/s relative to it. So they enter the portal moving at 1 m/s and exit at the same speed.