For a while now, I've wanted to know what the depth of the Nether is. I might've been able to just look it up (which I kind of did, but the wiki alone didn't say anything), but that wouldn't have been fun. So I made like Thanos and did it myself.
Excuse me if this has been done already or if it's wrong. I did what I could 
Note: I was using the term "surface area" incorrectly so I changed it to "surface distance".
So let's say we have a new default, vanilla, unaltered world. Its coordinates stretch, from its center, 29,999,984 blocks in all four directions.
It's been stated that 1 block equals 1 meter. So that's 29,999,984 meters, and if you divide that by 1,000 you get 29,999.984 kilometers.
Now, the important part: Let's say that this world ends at the world border. Technically a Minecraft world is infinite, but the space in which you can explore and build is finite. We'll also say the world is 2 dimensional and that it wraps around like a real planet.
29,999.984 km is the surface distance of only half this 2D planet. Multiply it by two, and you have 59,999.968 kilometers of total surface distance.
For now, I'll leave that number alone.
This is the Nether. It has its own space deep underneath the ground of this world. This information right here is crucial:
Every 1 block in the Nether is 8 blocks on the Overworld. That means that the Overworld's surface distance is the Nether's surface distance, but 8 times larger. And yes, the Nether in actual Minecraft is just as big as the Overworld, but that's a math problem for some other time.
I've been learning dilations in my Geometry class recently and so here's the perfect time to use them. I'll cut out a quarter chunk of the Nether and scale it up 8 times.
Now you can see how deep the Nether really is. But we don't actually know the exact number yet.
The top layer of this diagram is the Overworld-- the Nether's surface distance times eight, like I said before.
That means that the Overworld's surface distance for this fourth of a planet is 14,999.992 kilometers.
That number isn't actually important, though. What is important is learning what the radius of this Minecraft world is from the center.
The formula for finding a circle's radius is circumference* ÷ 2π.
Circumference is the same thing as surface distance, therefore 59,999.968 ÷ 2π = ~19,098.582985111082410964562396141.
I'll shorten that down to 19,098.582. That, in kilometers, is our distance from the very center of this world to the Overworld's bedrock layer.
You can see in the above image that the Nether takes up an eighth of the planet's depth from the surface to the center. That means the distance from the core that the Nether is at is an eighth of the planet's radius, which is 19,098.582 kilometers, and that its distance from the surface is seven eighths of the planet's radius.
Final verdict:
The distance of the Nether from the planet's core is...
2,387.32275 kilometers
2387322.75 diamond blocks
1483.4135834228 miles
The distance of the Nether, from its top bedrock layer to the Overworld's bottom one, is...
16,711.25925 kilometers
16,711,259.25 diamond blocks
10,383.8950839596 miles
2
Pillagers don't care about light levels. This isn't a way to stop them to spawn.
There's no solution for now to prevent them to come inside your village apart from switching in peaceful mode.
However, keep in mind that if you don't kill the pillagers by yourself, you'll not get the Bad Omen effect, so you won't start a raid. I recommand you to create some Iron Golem in order to protect a bit the village, or to kill them in a different way (make them following you and place them in lava / cactus / bush / make them fall without hitting them).
When you see Pillager, you can also make the one with the banner follow you outside the village, kill him and drink a bucket of milk in order to get ride of the Bad Omen effect before returning in the village.
1
Hi,
I presume you're currently playing on snapshot version. This issue happens when you change dimension, sometimes during the changement, the EntityTracker of the player get lost leading to several bugs.
Loosing the ability to fly with elytras is one of them. I let you take a look at the whole list :
https://bugs.mojang.com/browse/MC-92916
All you need to do is to quit/join the world again
(disconect/reconnect if on server).