XMPP servers and clients have different standards. Some supports audio/video calls

And the same is true about Matrix lol

It’s worth noting that you can rewrite history after the fact with Git

You’re overthinking it. Select a few of the popular ones and be done with it

I’m a programmer and it really is quite easy to implement lol

Make sure you understand volume block size before you start using it. It has a big impact on compression, performance and even disk utilization. In certain configurations you may be surprised to find out as much as 25% of your disk space (in addition to parity) is effectively gone and it is untrivial to change the block size after the fact.