1. At the end of your hubs you can put links of your related hubs by using the "Links" capsule. Within the Links capsule you can specify the links to your related hubs and they will show up in that capsule if the links are entered properly. I would recommend entering the entire URL of your related hubs in order for it to display within the Links module.
2. For your 2nd question, if you want to enter a hyperlink for a hub within a hub you are creating, then use the "link" button. It is the 4th icon on your tool bar from your right. Toolbar displays your Bold, Italic and Underline options. If you have further questions, please feel free to send me a message.