Questions on GameLift Plugin Nodes

[xdRedBallG]

Hello! I love this plugin but I have a few questions.

A. Should I run these nodes as a server or as a client? (Via The Has Authority? Node.)
B. What should I input into the pins where it says, “Key” and “Value”?
https://imgur.com/a/7ObZUAj
C. I see that you have made custom events such as, “OnCreateGameSessionSuccess_Event” and “OnCreateGameSessionFailded_Event”. How did you guys get the string values of error message and Game Session ID on your custom event node?
D. And my last question is that if I would implement a party system where you can play with friends, is this possible with the nodes or would I have to use C++. I would rather use blueprints because I am more comfortable with them.

Help is appreciated! Thanks so much!