https://hereistheevidence.com/
I believe it is the most comprehensive collection of evidence
The best (but probably slowest at the time) is having some kind of Blockchain technology. It would work alot like Bitcoin but would at the moment be infeasible due to spam and unability to regulate anything.
Another way is to build it with a scalable solution for database management right from the start. Like MongoDB is a great example. That allows for scalable databases with high performances. I believe if Twitter wasn't busy having all the hunts for conservatives through AI, they probably could implement that and be much better off. With that being said, I think that the next generation social media would be a well balanced-mix of those two.
It's hard to predict how to not be hacked, it's like saying how to go not be hungry. It's alot in how the underlying system is implemented, and the risk of having a distributed peer-to-peer solution is that it would certainly be easy to hunt down individuals with a strong node (much traffic going through) by their IPS's
Biden commented saying the letter was "very generous" so I assume it is fake