Low level questions regarding how MTA works

[redigaffi]

Hello!

Recently, I'm interested in diving into more low level topics to learn more. I've been looking through MTA code to get a slight understanding of how things work underneath, a couple of questions arise:

1. How are online players treated? Are they PEDS? (I assume yes)
2. If the above is true, how is the 140 PED limit surpassed?
3. I've seen to add players/NPC's Cworld:Add is called, which calls FUNC_Add (a function stored at 0x563220), where does this function come from? I can't find any reference/docs to it, I checked here: https://gtamods.com/wiki/Memory_Addresses_(SA), and Googled it, the only reference I found was in MTA and plugin-sdk (https://github.com/DK22Pac/plugin-sdk)
4. So, how can you call the add function from GTA process (a function in another process) at 0x563220 if MTA is running in another process? Is there a remote thread injected into GTA? A DLL? How does that work?, where is it done?

Thanks for reading!