1. Yes.  The Reflex is fine when lighting is the same on the target as on the sight, or if the sight is located in a brighter area, but if the target is brighter, the reticle will wash out.  At night with a bright light (as you're envisioning), there will be no visible reticle.  If you think you'll need a light (and many situations will require one), I recommend against the Reflex.

2. Any non-magnified "reflex/dot" optic works better (i.e., target acquisition is faster) when mounted forward over the handguards.  It also helps you to shoot with both eyes open, which allows you to detect movement outside of your optic's field of view.

-Troy