Welcome to the board!
Read the faqs, or do a search and you will find most of these topics have been covered in depth a number of times.
1. You can get details on the control types here;
http://fe.donkeyfly.com/controls/gamesbycontrol.php3. You can use an 8 way joystick configured via the mame settings for 4 way diagonal games (like Q Bert), rather than a dedicated diagonal 4 way. NoOne=NBA has described his method to accomplish the feel of a 4-way diagonal in a large number of posts.
4. Depends.
6a. Probably your print settings, rather than the applications.
6b. Maybe he doesn't play golden tee. I don't. I use my trackball for centipede, etc.
You don't need 7 buttons for player 3 & 4. Put player 3 & 4 on the outside with 3 buttons. 4 feet wide should do it for that many players.