Thank you all for your insightful comments and critiques. All viewpoints are very appreciated. CorporalCaptain (is that a M*A*S*H reference?), to answer your comments:
1. Yep, escaped me for that scene. You are correct.
2. I felt that six hundred years was long enough to build up to about a 1945 or so level, given that they had a pretty good supply of high tech do-dads to begin with, even if most were destroyed.
3. Other than specifying a vaguely military look for Sarat and Kalv, I don't think I indicated any type of clothing in the script. I could be wrong. I'll look sometime soon to see.
SPOILER: In re Grigory's motivation(s). Yes. Right on some of your suppositions, except your second sentence which says "Was it for r______?" and the "insect" analogy and Preserver intent. Those three issues never entered into my thinking. Sorry for the vagueness, but I'm too lazy at the moment to look up the spoiler code to hide my answers.