You can certainly use arrays and do your own memory management. The biggest component is that if you're creating anything that's an NSObject subclass, and you create it with a [XXX alloc] method, or if you get it from another copy with [xxx copy], then you've got the responsibility to match that with an associated release.
If get a variable from anywhere and intend to keep it around for more than the immediate usage that you're executing through, then make sure you invoke a [... retain] on it.
The link http://developer.apple.com/documentation/Cocoa/Conceptual/MemoryMgmt/MemoryMgmt.html has all the details, and is definitely the first place to read.
