Parts/Accessories Recommendations/help

[Lemming]

99' 1.0L 3Cyl

Okay, I just got a $500 gift certificate to some ricer autoparts store, and I am not a ricer. I have made a list of things I would like to waste the money on but would be open to suggestions. I am hoping people might know what I need.

-Battery: Max size that will fit? Parts number? namebrand? I have alot of audio in the car and would like to take some pressure off the alt.

-Cheap alarm system: Any recomendations?

-K&N air filter: Parts number?

-Car Bra: Name brand? Parts numbers? My bumper is cracked and the cheapest replacement I can find is $400 and well, I don't care about how pretty it is, atleast not that much.

Anything else, not sure what I can get off of this store.