ROM burning isn't rocket science, it's got a bit of a learning curve, but it's not steep!

Erase the chips til they pass a blank test with the programmer. There's no definitive time for a chip, will depend on the bulbs in the eraser, etc.

One tidbit - be careful with eproms with 'A' in their P/N - they often program at a different voltage than standard. A lower voltage. If you program them at the higher voltage, they *may* program - but they may not program - but odds are really good that they will erase again, but will never program again.

Don't bother with the sound ROMs, they never change.

You need a 27c512 for the CPU ROM and 27c040 or 27c4001 for the display ROMs. They MUST be 120 NS or faster, 150 NS will NOT work. The 120 NS or faster only matters for the DE/Sega games with the big DMDs.

The speed will be displayed on the chips, typically -12 = 120 NS, -10 = 100 NS, -15 = 150 NS. You may also find some 80 ns in some makes of chips.

No, a 27512 has 28 pins. A 27c040 has 32. Won't physically fit

And as long as they are all faster than 150ns, mixing is ok.