WIF, ADFS, ACS, OAuth 2.0 Questions

Hi all,

So far, what I understand are (please correct me):

• ACS provides a very easy way to setup identity provider (Google, Facebook...), I need to setup Windows Azure subscription and then setup the web.config file. To authorize user/role in code, I cast the Thread.CurrentPrincipal or HttpContext.Current.User to ClaimsPrincipal and invoke the method HasClaim or FindFirst
• For OAuth 2.0,  to authorize the user, I need to use OAuthWebSecurity class to do all the fancy things
• ADFS is supported on Windows Server 2012, and allows to do the similar things as ACS as well as to build your own STS service
• You can also use WIF to build STS. To enable WIF in your application to trust identity provider(s), I can setup web.config file to trust an identity provider/STS (trustedIssuers element)
• A custom STS can be built without ADFS by using third party framework

Questions:

1. When should I use Active Directory Federation Service, WIF, a custom STS, ACS, Claims Principal, OAuth 2.0
2. What are the requirements for using these methods?
3. Do ACS, OAuth, ADFS, STS always return ClaimsPrincipal object that are assigned to Thread,CurrentPrincipal?
4. If I use ACS, do I need to manually setup trustedIssuers element or the Identity and Access Tool complete the configuration?
5. Is the configuration always the same to setup trusted provider for ACS, OAuth, ADFS, STS?
6. Where are the claims stored if I want to add a claim using AddClaim method? 
7. Does Claim's type always have to be in uri format such as http://schemas.xmlsoap.org/ws/2005/05/identity/claims/stateorprovince?

Sorry for asking to many questions.

Thanks,

Sam