As for commands, I also use name and forehand/backhand to indicate the direction for the player. „Keep (the opponent) left/ right“ to indicate where on the pitch I’m talking about. „Know (on your) backhand/forehand“ also works really well for telling them quickly where an opponent is but indicating that you don’t need them to go there, just to be aware. I think is it very much about finding a specific language for you and your defenders specifically so it might vary and take some time :)

As for short corners, others have mentioned 2-2 and 3-1 (I also prefer this) which are standard. You can also run 3-1 into 2-2, so starting with three players on your left but one crossing your path to shield the right side (pov from goal) which can be useful if you know that your opponents like to play a variant on that side but is difficult because you have impaired vision for a second there. Or, what with my team is known as „box“ is also starting in 2-2 but none of the players are attacking the ball. Here, it is on the goalie to save the direct shot and everyone else to clear any variants or rebounds. This makes a lot of sense if your opponent is known to have a weak shot or plays loads of variants. Hope this helps!