Some configuration

I have a this configuration:
Long URLs:  No 
Lower case: No
Home menu URL: Yes
Unique item: No
Fish support: No 
Debug: No

But in my URL i see the name of section and i don't want.
What I must modify?

Cache Yes or No? And Why?

Thanks

You can't skip name of the section. The URL will always be like:
domain.com/section/category/item/

You can't have
domain.com/category/item/
(unless you use alias)