WordPress subfolders query

I am going to be setting up a blog and hosting around 10 subfolders. Basically one overall niche with a number of micro niches as subfolders. Just a couple of questions.
1/ Can the header and theme colour can be changed for each subfolder?
2/ Can the subfolders act similar to a subdomain where a users navigation is limited to that ‘micro niche’ folder unless they click on the home page tab?
3/ Can each subfolder have their own pages?

Trying to discern if what I am looking at accomplishing will work with subfolders (SEO purposes)
Thanks for your help,

David