I have some trouble understanding differences between "make an index" (default
do this) and "make a top index" (default don't do that).

I create all of my mirrors inside a folder, let's say "websites". Everytime I
wish to start a new project I create a folder for it, so let's create
"mirror1". Then I open a shell session and run httrack inside that folder
("mirror1"). That way I needn't any -O option.

Bearing in mind I do use both -I and -%i as options, will I have an index.html
inside "mirror1" and "websites"? Comment: that's not my experience, I have
only the one inside "mirror1".

Example: ~/websites/mirror1> httrack www.httrack.com -%i

I would be happy having an index.html inside "websites" listing and linking to
all my mirrors, but as I'm doing something wrong, how should I run httrack to
accomplish that? What are the differences between an index and a top index?