This book already answers most common questions in context rather than a separate list:
What is MLCast, and why nowcasting? → Overview
How do I install it and train a model? → Get Started, Usage
How can I contribute, and do I need a GPU? → Collaborate
Where does the data come from, and how is it validated? → Data, Validator
How are models evaluated? → Evaluation
For anything else, ask on Slack.