WRT the calculator ROMs, HP's gone back and forth on that.

• First, the ROMs were copyrighted, and HP would not license them for distribution. So you had to dump the ROM from your HP calculator (legal, under fair use), and use that.
• Then, HP slackened up and licensed them for free distribution for non-profit use. At that point, most emulators, including power48, distributed them with the emulator.
• Finally, HP revoked distribution with emulators, but permitted free download from HP, and also from other sites. Just not packaged with the emulator.

So I got the emulator from HPcalc.org. And I also got the ROM image for the HP49 in a separate package from HPcalc.org. And, because I wasn't sure what I was doing, I tried starting power48 with no ROM, then again after I loaded the ROM, to make sure that it was seeing the ROM. It failed in different ways, so putting the ROM on did have some effect.
So for now, I give up. I'm too busy, and tinkering with my N800 wastes too much of my time without an HP emulator.
Still can't wait for ITOS 2008, but I'd better get some work done so I have time for that.