1) The resolution. It's repeatedly reported as 640x480 (704x 480, 736x 480, etc.). However, no game or any software whatsoever for the system (though I haven't tried a photo-CD but I doubt it) uses any of these high-resolution modes. As the system is Japan only, it probaby doesn't even do the higher vertical (512) resolution. I believe the max to be 320x240 (and whatever overscan is required for full tv display). A few sites make mention of this. Then there's the hdtv bomberman thing, but Assembler seems to say this was on hardware very different from the actual pc-fx.
2) 9 hardware scrolls (parallax). However, I've been told from a reliable source that the well-documented GPU for backgrounds this is simply not capable of that. IIRC, that number was 4 scrolls. Perhaps including some software tricks it could happen, but that wouldn't then be hardware scrolls. Even if the overlay from another chip is used and we can include 1 layer from the fmv hardware and 2 from the HuC6270, that would be 7 involving some heavy hardware banging. Can we then get 2 more from the use of sprites? I think probably Zeroigar has the most layers of any software, being probably 3 or 4.