As I mentioned before, I don't have an nm-145, but since nobody's responded I might be able to help a little...
There should be a limit switch on the rear of the table with a sheetmetal cover projecting over it. On the nm200 it's about an inch wide.
Travel is determined by 1.) the limit switch trigger points (you can go past it but ref 0 will be determined by this, and you can set mach3 to not go past), 2.) oil line location/length (see the recent thread regarding this to see why it's an issue), and 3.) the ballscrew length. On the NM 200s2 the stated travel is pretty conservative. With slight modifications you can extend it. Again, the recent thread about the topic details it some more.
Unfortunately I can't answer specific dimension questions, but if you email Khai I'm sure he can get them to do a couple measurements for you.