I am tasked with migrating a .NET app to Umbraco, one that has a few thousand users a store locator and multi roles et al.

My questions is can I migrate existing users in to Umbraco as Members?

I'd like to be able to pass member credentials (like an ID value) as a querystring. I am expect that to be possible and am hoping there is some sort of helper class in umbraco so that I can access profile values etc within XSLT or RZR.

I'd rather not use too many User Controls but I guess I can place them on Dashboards.

Any advice gratefully received.