Which theme will suit my requirements

I am building a website on a subject which will have six / seven sub-subjects. The information under each sub-subject will be mostly static. I will keep on adding more information under each sub-subjects, which will not be very frequent.
With my limited knowledge (I am new & have just started), building up a site with menus with drop down sub-menus in horizontal bar under the header will be appropriate instead of using categories.
The theme which I am using is twenty eleven (basic) on wp. It came as preinstalled when I downloaded WP from Hostgator. This theme supports one menu only. I am also thinking of having a front home page as a master page which will have all the information which I add under each sub-subjects.
I request seasoned warriors to advise me on the following two queries:
Firstly, what I am thinking is right or if in their view there is a better option.
Secondly, which theme they recommend. As I am short of funds, I will prefer a freely available theme for my first site. For my subsequent sites when I am more experienced, I will go for a paid theme.

Regards....cbnet

P.S. (i) My aim is to monetize my site with various options. (ii) If adding of more menus (5 to 6) is possible on twenty eleven, I will prefer to continue with twenty eleven