First, thanks for putting in my suggestion about Enter key for race setup screen. But second, unfortunately there's problem with this too. The join function doesn't work unless you are first to join the grid, i.e. works only if large button on bottom right says "no drivers", otherwise Enter key sets "Ready" without joining grid first.
Also my idea was that Enter key should toggle "Ready", i.e. be equivalent to clicking that large button on bottom right corner, no matter what's written on it.
Thank you for attention. :-)