Just want to say this is a brilliant idea, and I wish you the best of luck. Not that you have to or anything, but it'd be amazing if we could have some pony related entertainment that Hasbro wasn't claiming to own. It's a good idea, and I like the setting you're developing.
Um... you might want to think about some overarching conflicts, world-spanning problems that take a season to solve. Also try to offer teasers hinting at even more questions, like how did the ponies get there, was there a reason they left the mainland, some inexplicable reason they get sad whenever referring to it? Or I dunno really.
As for titles, I dunno... I'd advise against "settlers" or "Horsearia" because you aren't really writing this for the location or the occupation of the ponies. Pick what you want to have in the entire show,
and call it that.
So let's see... ponies, explorers, mysteries, nature, wonder, friendship, helping, singing, cooperation... a title based on some of that stuff. "Pony Explorers" would be better than "Settlers of Horsearia" for instance. You could also add a title that changes from season to season, like "Ponies: Seekers of the Heart Song."
I don't think you... need
an audience surrogate character. Just make the characters all appealing in their own ways. If the audience wanted to see themselves, they'd go watch home movies. Stories are about exploring other people, and being able to identify with them.
IMO a good writer can make just about any
character an audience surrogate, at any given time, by showing us how we can sympathize with their motivations. You could even have the audience surrogate of the day be one of the ponies living there, who has to introduce the newcomer to stuff. Your batpony character could
be a new arrival to the town, which lets you introduce the setting to the viewers, but she doesn't have to have a fence-sitting, mediating, "totally cool dude" personality that conflicts with literally no one in the audience.
Maybe make her a uh... dingbat, like really unobservant or slow to draw obvious conclusions. Maybe make her slow to warm, like Maud Pieish, or too quick to warm, like Pinkie Pieish. Give her a real personality that isn't just doing stuff because the author said so, but give her some things she struggles with that the audience doesn't, or things she's super good at that the audience can only wish they were good at. Give her a reason