Well, the rattling is still the start-up rattling that I've been complaining about the past year or so. It only rattles when I start my car up when the engine is cool. If I drive it for about 20 minutes or so, the car won't rattle when I start-up the car until it cools down again. Yeah, I still need to try and get an audio of that again... But I'll try taking off the AC belt during startup.
As far as the battery goes, I did check it before when my IAC went bad and everything checked out. During that time though, the car was still rattling of course. But yeah, if I can't get it started when I get home I'll try jumping it with my dad's 4Runner.
Thanks for all the replies guys.