Cheaper than a real A500?
I bought my used Dreamcast for about $15 from a local gaming shop.
How to use real Amiga floppies?
Obviously, you have to transadf them and then you can pop them onto the CD. I don't think this emulator has been programmed to acknowledge a CD change yet (as most other emus for the dreamcast do, allowing you to put more .adf/etc images on another CD) but it's early yet.
I'm surprised the Dreamcast has the gusto to emulate an a500 at reasonable speed (happily surprised though).
It says virtual keyboard support.
It means that 'virtual keyboard support' has been added. Dreamcast Keyboards were your only option with the first few versions.