That is a lot of information to ask in a User to User forum.
Have you looked at the "Scripting" reference under LiveCycle Designer's "Help" menu option?
Adobe Users' Community,
http://www.acrobatusers.com/ , has a number of video tutorials about LiveCycle Designer and Acrobat Forms.
1) create a group of items.
2) you have to write code to insert each item into the next combo box.
3) you can use any number of actions and code to set another field to the value of a given field. The exact method depends upon how one wants the form to work.
4) LiveCycle Designer use FormCalc and JavaScript.
5) There is a predefined "Print' button and you can change the code as documented in LiveCycle Desinger's Scripting reference.
6) Yes.