I want a system where members can register themselves from the front end, either signing up as a new member, or signing in with their Facebook, Google or Microsoft accounts.

Once registered, the member is assigned the default privilege to preselected backend pages and frontend pages. An administrator should be able to change membership privileges to include more areas than what is provided by default for new registration.

I suppose this is the same as the use of member groups / role management (member section), or would it be necessary to be a user administrator (user section), or is it unnecessarily complicating?

It must be the most forward-looking of the various systems that have been used up to now for authentication, and that I can upgrade Umbraco when any new release are published. Therefore, I guess it will be necessary to learn to integrate systems such as ASP.NET Identity, and modify where necessary (or modify Membership, but I read that Membership is on the way out, so it's probably out of date someday).

Does anyone have a good idea for this solution, or at least I need some key features for best practice which technologies should be used these days?

I'm noticing that with Umbraco, Microsoft.AspNet.Identity.Owin and Microsoft.AspNet.Identity.Core are already innstalled, but not Microsoft.AspNet.Identity.EntityFramework.

Should I avoid Membership, and relate to ASP.NET Identity, and maybe also stop using Sql CE (.sdf), and switch to SQL (or LocalDb)?