Are AntMiners only for BTC and BTH plus some other minors ? What can WhatsMiners mine ?
Antminers(Bitmain) make different miners for different algos, but majority are SHA256, Whatsminer (MicroBT) only make SHA256 miners
Can you download software to these machines to configure them to mine anything ? Do they have operating systems ?
No you can't, yes they come with an operating system
Does each machine have two cables to devide the energy consumption if you use two outlets on two circuits ?
Antminer usually, because they use C13 which is not capable of doing the 3kw+ they need, Whatsminer use C19 a single cable.
If some miners have only one cable can you use something to devide it and use two outlets ?
Supplying a PSU that takes a single input from two different sources is probably not recommended, i have seen a C19 - male C20 Y cable which means the same input supplies two PSUs but not the opposite, i won't do that unless approved by the manufaturer.
Does WhatsMiner M21S specifically have two cables ?
Nop, only one cable