> 1) What is the memory size?

A MS630-BA (M7608-AA) is 2MB.
A MS630-BB (M7608-BA) is 4MB.
These are the same board but one is half-populated, the other is fully
populated.

The M7609 (MS630-CA) is 8MB.

So you have either 10MB or 12MB.

> 2) Am I correct in thinking this is a X.25 or WAN port? (connected to DB-25
> port)

The M7500 is a KMV11 or a KMV1A.

That's an awful lot of serial lines you have there !

Antonio