Saw someone make a hearth model in another question:

What is this?  I don't see any way to specify a new model in the CPE

I'm interested in:

• Is this vanilla classicube?
• Whence does the client retrieve model information?
• What model formats does the client support?
• Can a server tell a client about a new model?  How?

Models is a command you use to change your body and your motion

• What model formats does the client support?

 Blockbench!!! https://blockbench.net/

What is this?

GOOGLE

if that doesnt answer your question, -> models is a way for players to change a specific block or even themselves, and can even add mods to the game 

Ex.

 he/she made a yeti model they can upload it minecraft (or CC) which allows then to have that model in the game

As for the other questions idk man