It appears that ICANN is allowing the creation of top level domains. Instead of 'registering' a domain, you would essentially be signing up to be a registrar (you'd be giving out registrations on your TLD).
- How do they decide whether to accept/reject applications? (i.e. is notability a requirement precluding .michael for instance)
- Can an existing business register a TLD, or is it only a more general organization (i.e. "the museum society" instead of the "NYC Natural History Museum")
- How much does it cost?
There are various considerations for accepting an application, covered in the guidebook (PDF). Part of the process will involve the application going through several panels, including:
String Similarity Panel – assesses whether a proposed gTLD string is likely to result in user confusion due to similarity with any reserved name, any existing TLD, any requested IDN ccTLD, or any new gTLD string applied for in the current application round. This occurs during the String Similarity review in Initial Evaluation. The panel may also review IDN tables submitted by applicants as part of its work.
DNS Stability Panel – reviews each applied-for string to determine whether the proposed string might adversely affect the security or stability of the DNS. This occurs during the DNS Stability String Review in Initial Evaluation.
Geographical Names Panel – reviews each application to determine whether the applied-for gTLD represents a geographic name, as defined in the Applicant Guidebook. In the event that the string represents a geographic name and requires government support, the panel will review and verify that the documentation provided with the application is from the relevant governments or public authorities and is authentic.
Technical Evaluation Panel – reviews the technical components of each application against the criteria in the Applicant Guidebook, along with proposed registry operations, in order to determine whether the applicant is technically and operationally capable of operating a gTLD registry as proposed in the application. This occurs during the Technical/Operational Reviews in Initial Evaluation, and may also occur in Extended Evaluation if necessary and if elected by the applicant.
Financial Evaluation Panel – reviews each application against the relevant business, financial and organizational criteria contained in the Applicant Guidebook, to determine whether the applicant is financially capable of maintaining a gTLD registry as proposed in the application. This occurs during the Financial Review in Initial Evaluation, and may also occur in Extended Evaluation if necessary and if elected by the applicant.
Registry Services Panel – reviews the proposed registry services in the application to determine if any registry services pose a risk of a meaningful adverse impact on security or stability. This occurs, if applicable, during the Extended Evaluation period.
Anyone can register a TLD, though you'd better own the trademark, and others can file objections to your TLD application. Also, you'll have to be able to operate as a registry.
The costs start at $185,000. From the FAQ to which you linked:
Yikes, good luck, this is a highly complicated and politicised process, full of red tape. You can see the official starting point here: http://www.icann.org/en/tlds/tld-application-process.htm or just search for "ICANN TLD application".
Edit: apparently there is a "new" program, too: new gTLD program
The post you linked has a link to the "Applicant Guidebook" that answers all of your questions. For example: