for fastest lap and all laps, is it ok to record the replay instead of recording the race when you do it? it would be great so i wouldn't have to edit out all the extra runs.

As much as the replay is considered "proof" of the run (one of my runs where I forgot to turn recording on i submitted a replay and it was approved) it doesn't allow others to check the route you took very well (also you don't see the speed, nor when you use nitro) Honestly for all laps I just turn recording off and on every time i restart, takes 5 seconds at most and the time it would take to edit the video is far greater. And don't forget you still have to record the replay, sometimes few times when you feel like you can do better, which also takes a while.

There's no real difference between Replays and Live Runs, they're still proof.

I'd say that replays are valid as long as you show the time, but I prefer seeing the Live Run so I can see all the HUD elements. One thing to consider though is that replays might have a low tickrate which means that the replay may show things differently than the live gameplay.

Yeah, I agree with Kaopoke, replays are okay with times and things like that, but Live Runs are much more preferable.