Maizie: Their friendship could end up interesting if Shelby and Liv end up a little :| at each other. But Shelby likes having friends/knowing people who can be as equally outgoing and positive as she is.
Dani: There are definitely tables in the shop, and Shelby would encourage students to come study there (she'll be doing a lot of multi-task studying herself). They are around the same age/probably finished the same amount of school before the zombies, so I could definitely see them being classmates in at least one science/bio class. :)
Bunny: If Bunny still has her milk and eggs business, Shelby might just contact her to see if they could strike up an agreement to supply the shop. Shelby's Gram is a big supporter of small, local businesses, and there's nothing better than farm fresh eggs.
Kevin: Shelby would gladly have KC as a regular! I think she would probably spend extra time chatting also, since he wouldn't be as put off by her as some.
Amanda: I think Shelby is used to a lot of people thinking her optimistic outlook doesn't really have a place in the zombie apocalypse, so she wouldn't be very surprised by that. She's probably a little in awe of Amanda, the same way she's in awe of Nina.