They should be close to the woofer unless you're going to have an active setup where you could then correct any time alignment between the mid and the tweeter. If you're going passive, I'd recommend going close but it's not the end of the world if you don't. Placement pretty much depends on how you like your tweeters. If you like them like I do, you'd want them aimed right at you. If you like them a little softer, some people put them a little lower in the door or the kick panels. It's really all personal preference.