The right side of the axle is also pretty far forward, but it doesn't look like it because of the 'claw' type derailleur mount. This is common on bikes with horizontal dropouts and claw derailleur mounts - the right side of the axle should be pulled all the way back against the claw, and the left should be positioned to put the wheel straight in the frame.

The claw is held in position by the Phillips screw and a half-moon nut holding against the back of the dropout, so the axle will always be placed forward in the dropout.

As for the axle slipping, it does happen occasionally, but almost always on the right side as a result of the chain pulling the wheel forward. As long as the nuts are good and tight, the wheel will not move, especially on the left side.