#A3000
The A3000 will work with any Amiga monitor. It won't deinterlace or
display Super72 (800×600 interlaced) or Productivity (640×480?)
without a multisync.
The A3000 can use two types of memory chips (though all must be the
same). I think that you can have 4 or 8 megs of fast (plus 2 megs
chip) on the motherboard. Zorro-III cards for at least 128megs are
out there. A3000s produced in the last two years usually come with 4
meg, and I think they usually comes with the higher density RAM.
AmigaDOS 2.04 should be the OS version.
There will be some software compatibility problems if you run games
or particularly old and awful applications. Most productivity
applications work with minor cosmetic problems at most under 2.04 and
better.