When the game starts, the mouse only aims the cursor a few feet from the char, I can't do anything. Also not sure how to move. A window keeps popping up about a security alert.

This is definitely a game that shouldn't be played with a mouse, even though there's 'support' for it.
I assume you mean the red reticle: That's not related to your mouse, but an indicator of which direction you're aiming.
There's a second reticle that'll show up when a target gets into your line of sight.

You can press F1 during gameplay to bring up a screen of controls.