I'm trying to use Windows 8 Photos (Metro App), I tried to connect Photos App with my Flickr and Facebook accounts which both associated with a Yahoo Mail account, But it seems it requires a Hotmail account associated Flickr and Facebook accounts to connect. Am I missing something here...? or how to connect to Flickr/Facebook account which are associated with non Microsoft mail address?
AFAIK, it requires a Microsoft Account. You can create one, even with non-Microsoft email addresses. I've heard people complain they don't want a Hotmail account, but I've succesfully set up a Microsoft account for my wife with her email address from our internet provider.
In the signup page, don't click 'Or get a new email address', but just enter your Yahoo Mail. This will also be your 'username' (what you use to login to your Microsoft Account):
After that, you can login to your account and link to your Twitter, Flickr, Facebook, etc accounts.