Thank you :)
1. Yes unfortunately there are some differences with how the game runes on different systems so what works on one PC may not work on another. That said, Giga is way too hard so I've temporarily retired it in the latest update until I improve car AI.
2. Yeah I know that's frustrating. I will be spending time on improving the car AI so hopefully this doesn't happen as much.
3. Added in the recent update!
4. I've made improvents to this in the recent update. You can copy traffic light patterns and you can also cycle the pattern clockwise or anti-clockwise.
5. I am currently working on a better tutorial as I need to do a better job of teaching the player. Lane changing in particular lots of people find unintuitive so I'll put extra effort into that. Regarding signs, I want to keep the proximity restriction in place. Having too many signs close to eachother is extremely difficult to understand when you have larger road layouts and ends up just being messy.
6. Added in the recent update! You can add whatever arrowhead you want to any prexisting sign.
7. This one is a bit of a compromise. Finding a path for the car is currently quite laggy so I have it setup that it only check when you hover over the lane or press the start button. (I'll be improving this with future updates).