[ruddzw]

1. My view would be that I wouldn't mind being directed to a sign-in/up page upon clicking, as long as it was clear why I'd need to be signed in to do so. If I'm on yahoo.com, and I click on mail, it makes sense to ask me to sign in. But I certainly want to know that once I'm signed in, I'll be able to have mail.

2. Google, Yahoo, and Amazon use "sign in." Facebook and Myspace use "log in." I'd say it depends upon the use, but personally I'd go with sign in.

3. Since the functionality is somewhat limited before signing in, have sign-in functionality on the front page. That way the user gets to what they want with one less page. However, along with my previous comments of keeping the links there, they should lead to a separate sign-in page.