Entanglement was a multiplayer mod made for Boneworks that has since became non-functional due to its reliance on Discord networking services, that have since been shut down.
ReTangled is a port of Entanglement to steam networking.

All you need to do is just drag the .dll into the Mods folder, or install it through r2modman if you are using that.
...you just answered your own question lol. Syncing many objects at once with the current networking will lead to a laggy experience.
Yes. You can disable them through BoneMenu - Client Menu - Client Settings - Nametags. This will only affect your side.
It does now.
Make sure you have the exact same Custom Items and Custom Playermodels installed. The filenames of the playermodels must be the exact same for both users. Playermodels will not load when joining a server and you must either reload your playermodels or switch scenes.
You must join their game before they load into a Custom Map. Once you are in the server, they can load into it. Also, make sure the file names of the CustomMaps are the exact same.
It is recommended for the host to start a server before loading into a map to ensure that all syncs are stored.
Bonelab Fusion is a multiplayer mod made by an original developer of Entanglement for Bonelab. Its much better.
No. Probably not.
No. Probably not.
This is BONEWORKS take your behind back to BONELAB!!!!!