Yes, we have modest stakes in both PAL and LEO so you will receive rewards on posts with those relevant tags.

Miners are delegators with SP and are paid in tokens, so separate from staking within Steem Engine.

I don't understand your last question. Unstaked tokens can benefit from the price increase. There are no rewards paid out, earnings are compounded and reflected in the token price.

Hope that helps :-) More questions, just fire away - they may end up in one of my daily posts.