There are several comments about “There is no Offline mode”. But it is just hard to find in this “nice” menu.
Here are the steps to make an offline game:
CUSTOM GAMES
CREATE
GAME NAME
Enter some random character.
Click on the right lock button to change the game to Private.
CREATE
Click on the "OPEN SLOT".
"Add Computer"
START GAME
PS, I don’t know who designed the menu but I have never seen such a bad menu like this. 
It’s really more of a one-player online game you’re describing. If you were really in an offline mode, you could save your single player skirmish. You will see that the save option is greyed out and unavailable. Not to mention a 1p game shouldn’t have to be subjected to network lag as is the case with the “mode” you describe. It’s junk.
Everytime i select add computer it kicks me from my own lobby
And this way doesn’t allow you to enable any kinds of cheats. If u wanna test something in the new map that u downloaded for example.
It’s because it’s a LAN Game as opposed to a Single Player Game. Outside the Campaign, there is no true Single Player Functionality in the game. From what I can tell, all they’ve done in Copy-Pasted the Online framework to the Offline one as a stop-gap/placeholder measure (hopefully).
But this doesn’t allow me to save/pause the game & return to it later.
I don’t get it, am I doing something wrong?
No, you’re not doing anything wrong; the “Offline” Skirmish option is just the Online One, sans the Online Requirement. That means no pausing, no saving, no loading. You can still “play” it, but if you’re called away from the computer for any reason…well, that’s an auto-loss.