There are a few ways to drop in to a game of Gang Beasts. The easiest way is to use the Join Game button on the main menu, this will automatically put you in the next available game. You can also join a game by selecting a game from the list of active games on the server, or by using the /join command in the chat window. To leave a game, press the Escape key.
The kick button is the B button in Gang Beasts.
There is no definitive answer to this question as it depends on player preference. Some people may find skins to be a fun and important part of the game, while others may not care about them. Ultimately, it is up to the individual player to decide whether or not they think skins matter in Gang Beasts.