you can find the difference between the two versions in the feature list. pro version will be offered in about 3-4 weeks.
about the 3DGS registered name: have a look in the FAQ. It is only your real name (normally) I don't want your UserID!!! You can always upgrade to the pro later, there will be no difference in the prices.e.g.: I am not sure about the price yet, but I think the pro will cost around 30 euro, so consequently the upgrade would be 15 euro.

@gri: I don't know, but I think it will be the same like with the ODE.