I have a couple questions regarding it: the power supply has a +V and -V as well as ground. does it matter what V i use?
I think it's just weird labeling and "V-" really means "GND".
Looking at the spec sheet:
-V is the negative terminal of the 12V supply,
+V is the positive terminal of the 12V supply.
PE is the protective earth connection.
There is no "ground" connection, you are free to choose ground.
Note that this is an isolated supply, but the output terminals mustn't go too far from
earth (the input-output isolation is tested to 3kV, but output-earth isolation is only
tested to 500V)
The leakage current is under 1mA, which means the outputs could be floating
at mains voltage levels if not tied to PE somewhere - recommended unless you have
a genuine reason not to.
The first thing you should do when it arrives is probe it with a multimeter.
Definitely - your multimeter is invaluable all the time, check everything
you can and fewer expensive mistakes will happen. In particular you can
verify voltage and polarity.