To rotate buildings before being placing, roll the mouse wheel up or down. If you do not have a mouse wheel or are maybe playing on a laptop, hold SHIFT and press either A or D to rotate.
You can use ‘+’ and ‘-’ on your numeric keypad to speed up and slow down the game respectively. There are three speeds available: Normal, Fast and Very fast.
Co-op isn’t a separate game mode, it is a part of Multiplayer.
To host a Co-op game, go to Multiplayer, select the Host game tab and create a multiplayer game. Wait for other players to join your game.
Once someone has joined, you can drag one player on top of another player to form a team.
You can then drag one team mate on top of the other team mate to form a co-op team (you will see a linked icon).
Computer A.I. can be added to a team but cannot be added to a co-op team.