Wouldn't lower temperatures make them hypo? I'd expect higher temperatures to make them hyperactive due to increasing their metabolism, not decreasing their activity levels like you say.
I found I had the most success growing them by not feeding them.
I had my coke bottle hatching BBS in a bucket of water with a heater in it to keep the bottle at the right temp. I strained the bbs out through a net and apparently some slipped through the net into the bucket. They seemed to grow quite happily in the bucket.
No, you don't have to seal it, that would defeat most of the purpose of the rock.
Yes, it's generally best to soak it for at least a few weeks, I think a couple months with frequent water changes is common.
Some of your comma complaints are actually style differences. In many places in a list there is a comma before the and in the last item of a list. This serves to differentiate between items in the list that are combined or items that are just members of the list such as the above example.
I don't see why bare polystyrene would be a problem as long as any plecos or similar can't get to it and possibly scrape it off and eat it. I bet most of the plastics used in tanks are polystyrene anyway...