"private categories!" are possible - only "Viewable" for member, admins or registered wikidot accounts..
setup done in the site manager in the permissions for every category without the "_default check" box clicked..
1. you will need to make "all other categories" private (without the standard "_default" ? ) only viewable for yourself or some admins
2. if you allow editing/creating on your site you cannot prevent "hacker" with a very good knowledge of wikidots modules (Listpages, _template, Includes a.s.o) to "include" a part or all content of such "private" pages ofer %%variables%%….they can find out a solution to "read" some private parts..
- but onyl if they can create any "test-pages" or "preview" them..
for the last sentence ( map to an URL) i do not understand and cannot help, I believe