How can I replace [...]
 

at end of a post summary with [more]? Thanks!

I could just tell you where to change that within the Ata settings but... I just spent a couple of minutes "refinding" the setting and realized that the effort of looking was rewarded by remembering in the future. Let's just say the setting is easily changeable to anything you want. I would also encourage to wander through ALL the setting as Ata has an amazing amount of tweakability and you might find some pleasant surprises.

Larry, excellent advice. Maybe the sheer number of options can be confusing to some, but the richness of this theme is in the flexibility built into it, and you can't learn it without digging around. Trial and error is the best way to learn this.

Hi Larry, thanks much, I found the ATO settings for excerpts. My real questions is, is there a way to change excerpt parameter for ONE category, instead of all? Let's say I want to show full posts (instead of excerpts) in all category pages except for one category, for which I want to show excerpts. Can I do that? Thanks!

I'm pretty sure there are plugins that can handle that kind of stuff. Try searching the WordPress.org plugins area for excerpt. One plugin I like but probably won't do what you want is Excerpt Editor.