Thanks for the help. I think I'm getting there but still I'd like some more info before shooting.
It has a same kind of serrated triangle measuring thing that is circled in the first picture. The viewfinder has the black under exposure needle but it also has some other markings and needles. One for the +1 -1 adjust and one that I'm not sure about.
I'll take a picture of the cartridge compartment and I'll also try to draw what I see in the viewfinder.
And yeah the meter is quite slow....