99% of mods are Client and Server side. Servers are basically just Hubs to pass info from 1 client (the one in control of the zone) to other clients (not in control of the zone).

Use R2MM to make Modpacks (Thunderstore). Steam Workshop is not a thing for this game. (Mods are not officaly supported). Redistributing mods without permission usually results in some sort of action by the modder due to Licence breech. Most of us modders are using assets directly from the Unity Store and are under heavy Licence, other modders are proffessional coders and have strict licences regarding their code.

You can have as many mods as you like at any given time. Most mods are compatible with each other, incompatabilities stem for either broken, out dated or mods that edit the same thing.

Crash Logs are handled by BepInEx and decently informative.

Mostly game version isnt an issue for mods, only time it is, is when IG does some major changes to the game code (its Early Access after all) and when they do this mods simply break and stop working and stay that way unless said modder fixes it.