I'd certainly like to help.. but my experience with hardware is very basic. Actually, NES development has been the only reason I've even tried to learn about this stuff. Do you know of a good CPLD info resource on the web?

Pardon my ignorance about EEPROMs, but for the BRAM would an SRAM be more appropriate? And will the CHR EEPROM allow a program to treat it as CHR-RAM? It could be interesting if that could allow bankswitchable CHR-RAM.