If prompted to sign in after you already signed in, just click the "Sign in" button you clicked earlier. If AI appears annoying after you sign in, click the Knowledge tab at the top.
Direct access to a bug report or summary is no longer possible. MOS internally maps the bug ID to an unpredictable KI (known issue) number or a content ID.
Status codes for bugs are documented on various web sites, such as this page, or officially and more completely at an old Service Requests document.
How to get Oracle Support the cheapest way There're two easy ways. For consultants, you can ask the company you're helping to solve a problem that they add you to their MOS account list. Technically, once you're done with the help or consulting work, your account should be removed. But they may be willing to keep you on the list either for being nice or expecting your help soon. Another way is to buy a very cheap Oracle product for a few dollars. (credit to Jeremiah Wilton)
[Update 2016-01]