Two questions: 1. Does this work with private repos? 2. Are there traffic limits? (use case e.g. when I reach a HN Top 10 ;)
2. No, there are no traffic limits.
Suggestion: if you use a CDN or other methods to improve the performance make sure to point it out in the landing page.
Keep up the good job.
You can host almost anything there, excluding illegal content.
Commercial content is fine.