Re. #1: The information on that Wiki site has nothing to do with the Inquisit implementation. If you want to run the Inquisit script locally, download it and install Inquisit Lab (
https://www.millisecond.com/download/ ). If you want to run it via the web, you need an Inquisit Web license.
As for changing or adding any text that's displayed: Use Inquisit Lab to modify the script, i.e., change and/or add <text> and <item> elements as needed, have the applicable <trial> element display them.
Re. #2: You need to set up <port> elements in the Inquisit script, configured according to your needs. Set up a <trial> that "displays" the "start" <port> stimulus at the beginning of the game. Do the same for the "end" <port> signal at the end. Sending <port> signals works the same in Inquisit as displaying any other kind of stimulus (<text>, <picture>, <video>, etc.).
Before you delve into the Cyberball script, I'd recommend working through the tutorials in the Inquisit documentation. That'll introduce you to the basics of Inquisit syntax and should help you to make sense of more complex scripts you may want to modify.