from reading previous posts it seems customary to directly contact a potential supervisor. Nevertheless, the school I'm applying seems to have a central admission comittee. Still, the professor in question encourages PhD candidates to contact him. Do i have less of a chance if i do not write him prior to the application and does he potentially expect some content other than explained here. Also, isnt it rude to directly address a professor with their first name at first contact?
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.