Turn based board game

I am making a turn based board game like carcassonne where the player places a tile and then places a character on that tile.

Would the placing/rotating of the tile be done on the game mode which I think handles all multiplayer stuff, or the grid actor that contains references to all tile pieces?

Do I create the level with the grid actor in the level and then cast from the grid actor to the game mode and everything else, or should I spawn the grid actor through the game mode?

All grid tiles that can have a tile placed on them should only allow for specific tile rotations, I currently have an array of all possible rotations on every grid tile so that when I new tile is picked it can loop through all of the allowed rotations however this method requires a lot of casting which I do not like.

Also how can I test multiplayer on one device?