The chip is identical. I believe the only differences are power delivery and cooling design. All the AIB partners are given a little creative freedom on those particular features, but they still must meet stringent quality standards and thus aren't really all that different.
The STRIX offerings tend to have high quality capacitors and allow for slightly more power output. This means that you can often take the overclocking a little further on the cards if you choose to. Unfortunately this sort of action would void the warranty of the card with PCS so it's not often a favoured approach.
It's a very expensive price to pay for not any additional benefit. Resale value would carry across though
None, it's all down to market rates at the time. The 2000 series for instance sold just as much or higher value than they were new.Is there a rough estimate to lets say if you have a 3000 series Strix card, to what % the price drops for when the next series of cards come out?