Questions about iOS betas

[Saberon]

I have a few questions about the iOS betas and whatnot...

I finally bought myself my first Mac computer, the MBP. I now (finally) have the ability to install iOS betas rather than just watch videos online..

Back in Feb 2011 I had a "friend" register my iPhone's UDID with his Developer account. Is that all I really need to do to be able to install the beta aside from having the actual .ipsw file? If I wanted to join the Developer program myself could I register my iPhone's UDID under my account or is it forever locked into my friend's account?

Also, assuming that iOS5 will be the next iOS beta version, is it possible to downgrade to iOS 4.3 from the iOS 5 beta if I needed to?

Finally, if I installed the beta on an iPhone without the UDID registered does it brick the phone? Or can it be somehow restored to a non beta version?

Thanks so much

 

[eseminario]

Beta versions of iOS are almost the same versions that apple launches everytime. The purpose of Beta versions are bugs cleaning, but overall is the same ipsw file.
I don't know if apple developer program brings tools to downgrade iOS, but there are lot of tutorials on the web.