As for pax taking their bags:
I wonder whether the pilots or CC of this aircraft took their bags ...?
I've never been in a slides-type evacuation (must fly more so the odds catch up). But it seems to me that some are more urgent than others. In this case, without having been on board, I'd guess that the situation wasn't of the "Get out NOW NOW NOW or you're dead!" type. The aircraft was in pretty good shape (considering), the crew may not have perceived imminent danger of death – in fact, there was none – and the evacuation may have been calm rather than rush. In that situation a SLF, looking out of the window at the climate, might be forgiven for getting her coat out of the overhead if she wasn't wearing it! And, of course, her handbag.
Then, of course, there are other factors for SLF to consider: they might anticipate long delay in getting their bag back if they didn't take it with them; and they might have read the frequent reports of passengers' baggage being looted after crashes.