1. Will I be able to run the Radeon at 1920x1080?
I think it should work. Years ago I opened a 2048x1500 screen with my PicassoIV so Picasso shouldn't limit that.
2. I think I've read somewhere that the Radeon is not usable in OS 4.0 due to a lack of drivers. Is there a PCI video card that is equally supported in 3.9/4.0 or would I still need the CVPPC in 4.0?
Voodoo3 is compatible with both OS3.x and OS4.x. Perhaps you can make it work disabling both PCIgraphics.card and Radeon.chip in kicklayout file. But I don't know if it will work.
3. I've got a few of the D-Link PCI 10/100 network adapters that are listed on their 'supported' page. Will this work in both 3.9/4.0? The 4000 currently has an Ariadne in her that works fine under both and need to maintain that level of connectivity.
OS4 won't be able to use PCI cards that require DMA. You will need a RTL8029.
4. Any downsides to running the Mediator instead of the standard daughterboard? Are power requirements higher etc etc? This 4000 has an ATX power supply fitted anyway but may look at getting another Mediator for a 4000 w/standard power supply.
It sucks power like there was no tomorrow :-D ATX PSU is not mandatory but a very good idea if you plan to have various pci cards, zorro cards, cvppc, HDs...
5. Using a Soundblaster 128 audio card has no effect on the audio quality of games does it? I don't do much with Amiga audio..just gaming.
OS-friendly games that use AHI will use SB128, 95% of games won't use it.
6. Does the Cyberstorm RAM and Radeon RAM (configured as fast) stack or is it use one or the other? Would the RAM access speed to the Radeon be faster than the Cyberstorm?
It would be nice to hear about any other notable experiences people have had 
Many thanks
If you want to use 1920x1080 resolutions a Voodoo3 may be handy although a CVPPC with a Deneb would be a nice combo. Using a Radeon will mean no Warp3D support and probably no OS4 support.
BTW, keep in mind that although Voodoo3 graphic chip is faster than Permedia2 some old Warp3D stuff won't work due to the lack of 15bit screenmodes and in addition to that Mediator(ZorroIII) bus is slower than CVPPC bus.
