1 & 2. I would start by ensuring your graphics and audio drivers are up to date. Second, you can turn off anti-aliasing via the in-game console for a slight performance boost. You can also turn off anti-aliasing through your graphics driver control panel.
To turn off anti-aliasing in-game:
Press ` on your keyboard, followed by Enter.
Type: msaa 0
3. Sounds like an input issue. If you're on a laptop, your touchpad might be causing this issue. Try disabling the touchpad device, or any additional input devices for that matter, like a gamepad, etc.
4 & 5. Crashes and minor bugs are to be expected since the game just launched, but if you could, reload an earlier save file and try again?