No... That's a line-level output and these are not powered speakers. You could buy a stereo or surround-sound receiver to power these speakers and use a stereo 3.5mm plug to dual RCA plug adapter cable (or cables for surround sound) to connect the sound card to a line level input on the receiver (CD, DVD, tape, etc...).
I also made shelves, as I have small children and stands would be dangerous to both the children and my speakers/entertainment center. Many others I have spoken with have mentioned that they use speaker stands, but choose wisely as these speakers are big and heavy for "bookshelf" speakers.
They do not have screw holes for mounting against a wall. These are also huge for bookshelf speakers, so you should probably look into stands instead of mounting them. Also, there is a bass port on the back side.
If they are really thin, they aren't 16 gauge as that is a fairly thick wire gauge. They are probably close to 22 gauge which seems pretty typical wire to ship with this kind of product. You are probably going to want to order some 16 or 14 gauge wire to go with these puppies anyway.