Second problem, a friend and I like to play it together, and, everything's better with mods, right? Well, we - or I suppose just I, since I host the server - downloaded a fair amount of mods, which I'll post a picture of below. I believe I installed them all correctly, and I think they're all compatible. But in game, we get a continuous streams of dozens of different errors. Sometimes we can't even see the chat because it just fills up with errors. I have a few less issues than the friend does, which I believe is because I'm hosting. Sometimes he joins in and will start placing blocks, but has an infinite ammount (we're in normal survival) and when he relogs in, every block he placed is gone.
So, here are the mods.

Thanks in advanced for any solutions to either problem.