Both are possible. I have a DKB Kwikstart board in my 1000 that lets me use the ROMs from the A500/2000. It did require some soldering work to install... you have to remove a PAL chip in the 1000 & replace it with a new one. There are also a couple of wires to add. I believe there is a hack on Aminet to do the same upgrade.
For the HD, that's also possible. As others have said, a 500 external HD will work, just plugged in backwards, since the slot is on the other side of the machine. You might have trouble covering up the mouse & joystick ports with one of those.
There were some A1000 external HDs built. There were also some external Zorro II expansion boxes for the 1000 that held cards made for the 2000. I had one of those with a CBM 2098 RAM card and a Trumpcard with a 50MB HD. Worked fine..
There is a hack to build a single slot adapter on Aminet.
-Jim
