Before spending money on "lazy summaries", I'd like more info. I also want to reverse the order of my posts from oldest to newest but in one category only. I will have an "introductory" category that should be read in order. And when this category is displayed on a group page (or do you call this a summary page?), I want them to also be oldest to newest.
However, in other blog categories, I want them displayed the usual way - newest post first. Is all this possible?