Well I am not sure if this will help or even if it is going to do what you are asking....
However, in the CP it does have a tab under Registration Settings, which is the registration screen which can make you hide a lot of the things you are saying here.
It has three settings,
Hide,
Show,
Show + Require.
Not sure if this is what you mean, but that is what the stock code has to offer. (as far as I can tell)
Dunny
