If you download the zipped bios from the site, inside there's a readme file with quite a lot of info.
About input crossing (it allows coin button to be used as select in home mode, and selct button to be used as coin in arcade mode), I have it enabled, although since I have a 1-slot with freeplay and select wired it's pretty useless. But it is handy if you don't have both the select and credit button wired.
I think that EU mode is almost the same as US, it's just that a few games have more censorship in US than EU.
I usually have the system on Arcade/EU.