Shun, dear - there is a multitude of ways to address someone in Chinese, like I mentioned before. One of the ways to show familiarity is to add a suffix or a prefix to the name. In this case it was Shun-er, but I think “Shun, dear” carries across the vibe well enough.

Bro - this should not be taken literally (which is why I didn’t use the more direct translation “big brother”). In Chinese it’s quite common to call other people by some sort of familial title, even if you’re not actually related to them, depending on their age and relationship with you - like uncle, or grandma, or brother/sister, etc. It’s quite common in various media to see the leader of some informal group (a group of friends, a gang - that sort of thing) to be called dage (big brother) by the more junior members of the group. Here, the meaning might actually be closer to “boss”.