If you link all of your blogs together in a circle that would be a link wheel, and if it's a closed wheel that could be considered as black hat seo so I wouldn't close the wheel. but you can only benefit from those blogs as
1) they will be considered as backlinks
2) they will drive traffic to your hub
3) no, they will probably not replace your hub, that is if your hub is full of quality content, make the blogs relevant and you have nothing to worry about!
4) using the same keywords will just make your hubs more important and relevant on the subject, so that is a must