Parks and Recreation/WMG

Leslie Knope is a clone of Hillary Clinton.
Hillary Clinton determinded that she's getting too old to be elected president, and so she created a younger clone of herself to take over her quest after she's gone.

Amy Poehler, who plays Leslie Knope, played Hillary Clinton on Saturday Night Live. She, too, is a clone of Hillary Clinton.

Tom is an art lover
There's his reaction to the abstract painting in "The Mural" and his photography in "Summer Catalog."

April's "disaffected teenager" persona is partially an act.
Like David Brent in the U.K. version of The Office, April is playing up for the cameras, except she's trying to come off as a sarcastic Daria-esque voice of reason/apathy. As the show goes on, April gets used to the cameras and bored with her act, so she starts to act more like herself. In short, she really is like that to a degree, but she was deliberately playing up that side of her personality in the earlier episodes.
 * Downright plausible, this.

Ben will run for mayor of Pawnee
This way he and Chris stay and he has a chance to redeem himself.

Andy is the grown up version of Finn the Human

 * And Jerry is the grown-up version of Charlie Brown and Leslie is the grown-up version of Bessie Higgenbottom.

And following up to that...

Leslie really IS a grown up version of The Mighty B
Or at least Nickelodeon paid Leslie to make a semi autobiographical animated series about her childhood and her years in Girl Scouts and her talking dog.

Leslie's dad is alive.
Her exact words were that "he LIVES in Florida in a cemetery". They never said he died.

The Aside Comment/mini-interview sequences take place in the characters' heads.
Unlike The Office, it's never stated that a documentary is being made about Pawnee's Parks and Rec department. Most of the time, when characters do two or more aside comments in one scene, they don't speak as if they know or remember the scene; they speak as if they are thinking of the comment while the scene is happening. When characters interrupt or comment on each others' asides, it just means that they're thinking aloud.
 * Not exactly true. In the pilot, Ron Swanson acknowledges the presence of the documentary crew, asking them if they got a grant to make this. But much like The Office, the format is certainly a stylistic choice more than anything else, and they don't make a great deal of effort to maintain this illusion.

So, what's a staunch libertarian doing in local government, anyway?
The answer is obvious, and comes down to two things: the theory of gravity, and Ron's moustache. Just astronomical bodies are drawn to orbit objects of greater mass, so too are powerful things. Ron Swanson's moustache is patently one of the most powerful things in the universe -- far more powerful than local government, and probably comparable in power to Ron himself. Therefore it is inevitable that local government is drawn to orbit around his moustache and, by extension, him. He can't help it. Or rather, he can help it, but only up to a point -- if that moustache were attached to a lesser man, it would be running Nebraska -- or possibly America -- as a totalitarian dictatorship. Only the raw power of Ron's disdain for power can counteract its awesome influence. We should all be grateful to him.
 * what
 * This also explains Stalin. He was a much lesser man than Ron.

Ann will eventually date Tom.
She has been shown to be able to date self-centered guys before under the right circumstances, and in turn, Tom has been shown to have some Hidden Depths and has liked her since the first episode.
 * I would argue against this only because while Weakness Turns Her On, Tom is so weak that even Ann finds it annoying ("Bowling for Votes").
 * Confirmed at the end of "Operation Ann".

Lil Sebastian chased Tammy One out of Pawnee.
She is widely considered to be a terror. No one but the mighty Lil Sebastian could get rid of her. Why else would she wait until he was dead to return? It also explains why Ron loves him so much.

Tom has partial immunity to Snakejuice because he taste-tested it a lot over the development stage.
The character sheet points out that him only being a bit affected by the otherwise powerful drink. The answer is simple: he and maybe Jean Ralphio were the only ones who would taste test. Over time, he built up an immunity to it. Hence why he wasn't knocked out flat.