1. I think you mean an accelerator by "Apollo", yes an accelerator is really required if you are serious.
2. Some m68k linux distros are available, I've never tries them, and I think there is a ppc debian distro, maybe others.
3. Yes
4. PCMCIA; No, but you can add a graphic board eiter through a zorro/pci busboard or through a ppc accelerator.
5. Yes, there are PCMCIA ethernet cards that work with the amiga, look for cnet.device and 3com/3c589.device on aminet.net. Amiga browsers are a little outdated but you can get by easily.
Others can expand on this, I just can't be arsed now, I thought I could when I started, but I can't :-)