Well, here's how it goes. You've got two VGA outputs, which give you either output from the card, or just output from the Amiga's native graphics. You can actually swap which one is mapped to which output, which I guess is handy if one of them is damaged.
You can also rig the Amiga's native output to a BNC (BriberyNCorruption

phono style connector, although that will probably take an extra cable you might not have. You don't really need this, it doesn't insist on PAL (Pablo does).
Not all Picasso IIs might support these options. There are a few variations.
It's nice to be able to control a framebuffer without the controls (The amiga native output) being visible on the 24 bit display. There is also probably an alpha channel option in there somewhere, and proably fading and toggling screens around (controlled by software, probably with an ARexx port for automation).
You don't necessarily want to have to run 24 bit graphics mode all the time. That means loading Workbench or another operating system fully. If you are playing games through the native chipset, don't bother loading drivers for the card, it's just a waste of resources, because madame blitter Agnus does not talk to 24 bit cards. If you are playing games with RTG 24 bit output, or using 24 bit applicatoins, or you just want a reource heavy but beauriful Workbench, it's a different story.
And pages 18-24 of the manual go over the resolution versus refresh rate issue in substantial technical detail, but appear to confirm the English language web reference.
Whether those refrersh rates match what you can get your hands on for a display or displays is the crucial issue, really.
