Contacting a potential PhD supervisor
You question has multiple elements, I will try to answer each of them:


I would advise against using first name. Just use Pr. LastName, which is formal, polite and concise
It is better to write him prior to the application and this can greatly affect your chance. By all means, it is likely that the central admission committee would contact your potential advisor or that your potential advisor could speak in your favor to the committee. You will lose nothing out of asking him beforehand. If I were a professor and I got an applicant that put my name as potential supervisor without asking me first, I would be slightly uncomfortable.
The answer you have quoted gives sufficient information I believe. A concise statement of your research interest, some articles of the professor you have liked to show you have read his work, your grade transcripts and your CV. All this combined should be perfect, just do not write an overly long e-mail and always remain polite and formal.


Like I said, you can only gain from writing the potential adviser beforehand.