I am fairly new to MAME, and would appreciate any help in answering the following questions:

1. I've read version 5 CHD's are for MAME 0.156 to 0.159 (current) only, is this true?
2. Will lower versions of CHD's other than 5 work on MAME 0.159?
3. Do I actually need CHDs to run the ROMs, if so, is there a specific list somewhere I can reference?
4. Is there a list somewhere, of working CHDs for v0.159 MAME?

Thanks again for any help you can give me.