I think that it would be quite cool if you could actually change the default and currently unchangeable buttons. Example:
Moving the tyre temp screen button from F9 to, for example, the button C.
I don't think it's currently possible directly from in-game and it would be a pretty neat feature to have

The other thing I was thinking about was adding a notification for when you are approaching cars with blue flags, maybe it can be toggled on and off in the settings as its possible that not everyone will like it, somehow.

You can.

Just bind C button as "press F9".

I've got tyre temps and susp on my wheel buttons.

Like this.

Yeah I know about that, but I was wondering if it would be possible to make it directly like the other controls as most new guys won't know that you can do it like that.

Also now that I think about it, it's impossible to use that on normal keys (without using alt+func buttons) for people that aren't on wheels