PCs can be any other nationality you wish; note that, due to the mores of the time, an obvious non-Caucasian in white society is likely to suffer some minor level of Social Stigma.
There are both Martians and Venusians (not 'Venereans', because that sounds like a disease
). Venusians are scaly frog-like humanoids with bad attitudes that like to lurk in swamps and ambush outsiders with poisoned spears; Martians are tall, spare humanoids with enigmatic attitudes and dusty-red skin. They carry spears (non-poisoned, but the heads are made of glass and very, very sharp) and strange-looking bows. Neither are available for use as PCs. There are no Venusians on Mars to date; the climate would not agree with them.
There are no indigenous people on the Moon, as it has no air, obviously
. Exploration has not yet revealed any other races in the solar system - yet.
Technology, as mentioned above will be set at TL5+x, with x indicating how far science has gone along the steampunk route. Anything to do with high technology will involve brass, steam power and/or clockwork. Biological
science has only gone as far as equivalent to TL7, although due to the Great War, clockwork (and possibly steam powered) prosthetics have started to make an appearance.
If there is something specific that you want, you have to ask.