I've been working on a survival world in Minecraft 1.14 recently and I've considered installing some of the datapacks used in Hermitcraft S7 (Vanilla Tweaks, by Xisumavoid: https://vanillatweaks.net/picker/datapacks/), and they seem to be worth installing. However, I do have a few general questions about datapacks since I haven't really seen the installation process or used them before.
How do you install a datapack? Is there some sort of datapacks folder, and is this for all your worlds regardless of version (of course not in previous versions w/out datapacks), only based on the version you put it in, or predominantly world-based?
What changes do datapacks make to your vanilla world, other than adding their intended feature? Do they change the world to become unplayable if you aren't using the datapack/unplayable for other players who don't have the datapacks, and will they cause any issues with your playing experience (such as FPS, lag, etc.)?
Will datapacks pose any risk to my world? Will they cause corruptions or break the world somehow? Or can I rest assured that it will run essentially like vanilla minecraft with no added risks?
Will datapacks made for versions higher than your current one work? I am planning on using the Wandering Traders datapack that unfortunately is only for 1.15, so should I use the datapack like normal, or should I stay away from it to avoid corruptions or glitches? Also, what happens if I join the world with the datapacks (if possible) in a lower version (like 1.13?)
Do datapacks work more like vanilla minecraft (like plugins), or do they work more like mods (game-changing additions)? It seems like they mostly just seem to be like plugins, since they use only vanilla items and features, but just wanted to clear this up before I install them.
Should I backup my world before installing datapacks? I'd like to be safe than sorry. Also, can datapacks corrupt other worlds, or potentially Minecraft in general (requiring some sort of hard reset)?