Can someone just go and walk from the parking to the skyline walk to see the view for free or how does that work? Also this would be at about 10pm is there a certain time you cant go anymore?

After 10pm street parking is free. You can stand on the street take some pictures and drive away, you can not take long space without paying parking.

Yes you can just walk along the lake and get great photographs. You pay and park at designated spots or you can park on the street right next to lake, this icon on Google map, for free (not legally allowed for an extended period of time) and go a few quick photowalk. That's what most people do there, as far as I have seen. I'm sure 10 pm would be fine, I was there fairly late, for night cityscapes.