1. Is the CM-64 100% compatible with the MT-32 as far as playing old DOS games goes?
2. Does it sound the same as the MT-32 when playing those DOS games?
For
realistic intents and purposes, yes, but
technically, no. As far as compatibility is concerned, the first two MT-32 versions feature "bugs" that are exploited in a few cases, resulting in sounds that are only correctly reproduced with a non-"newtype" MT-32.
3. Does it have an LCD screen for midi messages? From what I can see, it does not.
Correct.
4. Can I use the same midi wire and big-to-small midi converter cables I am using now to connect my MT-32 to my SCC-1?
Yes.
5. Does this unit suffer from the buffer overflow error?
Not that I've heard of.