[development] node caching

Sorry for jumping into this late in the game, but I was only aware of node caching after it went in. Just for my edification, please explain how, in Drupal 6, how one handles these three situations: 1. dynamic data 2. role based differences between loaded nodes 3. node_access based differences between nodes. Please understand, I'm a great fan of caching and would love to see node caching; I just need to understand how module programmers are supposed to handle these cases, since in D5 they could do all of this in nodeapi without cause for concern. Thanks Robert