Impulse Response Cab Sims Explained Better

What’s the basic difference between and impulse response and an analog cab sim?
What type of impulse response do I need for my Mooer, Hotone, Two Notes, etc?
What length of IR should I use?
What exactly do they simulate? Do they include the effect of the air? Mics? Or is just simulating what happens before the sound hits the air? If so how does it interface with cabinet simulators that model things like mic placement.

Why not analog? 1:04
What type of IR should I use? 2:47
Sample Frequency? 3:10
IR Length: 4:20
Parallel IR’s 5:06
Comparing IR cabs and speakers 5:50
Examples of parallel 7:29
Examples of IR length 10:16
What’s the difference between cheap and expensive IR loaders? 13:26
More examples of IR length with room IR’s 14:37

Video links:
   • Pete Thorn- Recording Guitar With Loa...   pete thorn

How long does an IR have to be:    • How long does an Impulse Response hav...  

Guitar speaker frequency response: https://wgsusa.com/blog/what-guitar-s...

Info about Celestion impulse response: https://www.celestionplus.com/ir-mic-...

I’m using this impulse response mostly in this video:
https://www.celestionplus.com/product...

Go waaaayyy off into the weeds regarding bits, samples, and etc:
   • D/A and A/D | Digital Show and Tell (...  

For even MORE fun: https://www.xiph.org/video/