[Rol_Lei Nut]

But does this lightmeter take a spotreading or is the area bigger and measures reflected light as my camera does?(Pentax MX)

Chances are that it has a fairly "wide" measurement area, as most older "normal" meters did. But certainly not all!

Also, does it have a Selenium or CdS (or other) cell? (i.e. doe it have a battery? - if not, it's selenium, which usually covers a fairly wide area, dependent on any microlens arrangent placed in fron of the cell).

Best would be to do some creative experimentation, trying to work out just what the meter is reading - a good idea anyway, even if you already know what the theoretical coverage is.