I have a suggestion for the pitcher selection problem.
You set your rotation 1-5 and once you enter the game, it is frozen for the next 5 games.
They can either let you pick who you want or your starter follows the order you set them in.
Once someone is picked they cannot be used until the 5 game cycle finishes.
As for starters out of the pen.
Accounting for the opener, you are allowed to use one starter per game. So you can open with Ryne Stanek and then bring in Kluber. But that's it no more starters.