You can open a business account, which is more restricted type of account, just for fan pages and ads. But you can't if you already have a personal account - personally, I can't see the advantage - it has a lot of restrictions on it, you'd just as well have a personal account, and not put much detail into it or bother to collect 'friends'
My fan pages were all started with personal accounts but they are not associated with my personal page. In other words, a person that is visiting my fan page does not know that I started it.
facebook is the best social networling site, this site fanclub and suggestion for aad friend is very nice
Fan pages are already private from what I can tell - unlike groups that show the originator, fan pages do not.