Regarding this being a "PG" jam, does that mean just nudity/adult pleasures are banned, or does that include violence and language? 

I ask because I've just finished making the mechanics for my entry, and they include the player getting to wield a comically large cleaver (made from the bottom 2 rows of the train track horizontal sprite and intersection sprite). I already have a particle system for sparks and dust, but I'm wondering if it'd be a problem to have blood splatter and partially drawn sprites for severed bits.

I'd also like to know if the restrictions on art assets also includes the image for the png cart and for showing before the game is clicked on when embedded. If it does, I'll just use a gameplay screenshot, but otherwise I'd prefer to draw something fancier.

If it is comical like Super Meat Boy, that's fine.  

I mean I don't really care about the cart label.  One could say it would be hardcore to make it out of the assets, but it is probably okay since it isn't what gets run as a game.