Yes, they're region free, so it should play the physical disks just fine.
Does having an import console impact game downloads and access to the marketplace? I play imports on my Vita, but the console is US.
I doubt it, based on the reviews for that particular item. Sounds like others use it without any issue. I'd buy it if I didn't just shell out for an Elite console from AWD. I can tell the difference in simple loading instances like when pressing left at the home screen to bring up the sidebar full of options. It lags a bit on the standard 1TB console I have, but it's noticeably quicker to transition to it. Also the transition to OneGuide and watching TV seems a bit faster too. Controller customization is nice too.