A few questions about running Stepmania in beat mode

Is it possible to do any of these things without modifying the source code:
* counting simultaneous notes seperately (as opposed to one "jump" like DDR etc.) - so if you were to hit one note but not the other the first one would still register as a hit rather than just getting one miss for both
* banners, backgrounds and preview music for BMS files - figured this one out, it's really as simple as putting "banner.png" and "background.png" in the folder with the BMSs.
* changing the keys used to navigate the menus (using the scratcher instead of keys 1 and 3 etc.)
* custom modifiers (auto-scratch turning scratch notes into autokeysounds, mirror mode not affecting scratch column etc)

Also, I noticed that in the latest version(s) of Stepmania, centre 1 player appears to be forced on for beat mode, even if turned off in the menus and ini file. I can't figure out how to make the note field appear on the left hand side as normal. Is this intentional?

Cheers for your time

Preview music for beat has been added in SM 5.0.7. You need a preview song defined in the BMS file, though.

Awesome, thanks! Works just as expected.
Just wondering, is it possible to have the preview music loop seamlessly instead of fading out at the end (like how it's done in online mode)?

Also, is it possible to have "custom" modifiers such as auto-scratch (turning scratch notes into autokeysounds) or mirror/random which doesn't affect the scratch column as Stepmania's does?