Sitemaps - Official Guidelines and Advise Please

Good day,

I am rebuilding a very old website.
As I hope you all have experienced - over time a site get's cluttered and one easily forget to maintain a clean sitemap structure. Contents just gets hacked in without any really SEO thoughts or consideration.

So now I am re-doing it all.
Want to do the entire sitemap structure. Group similar information properly.

But what I need from the Gurus here - is a some advise and solid guidelines.

1. Is there a "SEO" ideal number of levels deep a sitemap should go? 3, 4 or 5 levels deep for example/
2. In order to have my keywords in my URL structure (relevant content though) would it be valuable to group pages in subfolder containing my keywords? When consider point #1. Which one carries more weight? Number of Levels vs KW in URL (subfolders)?

A typical challenge I am facing.
I have content relating to:
"Sign Language",
"Sign Language Software",
"American Sign Language Software",
"American Sign Language",
"Spanish Sign Language Software",
"Spanish Sign Language"
as an example. I am also targeting these keywords for my rankings.

Would the following example make for any SEO?

Example #1:
-----------------------------------------------
Home
----- Pages
Download
----- Pages
----- Pages
Products
----- Pages
----- Pages
Sign Language
----- Software
--------- American Sign Language
----------------- Pages
----------------- Pages
----------------- Pages
--------- Spanish Sign Language
----------------- Pages
----------------- Pages
----------------- Pages
----- American
----------------- Pages
----------------- Pages
----- Spanish
----------------- Pages
----------------- Pages
----- For Babies
----------------- Pages
----------------- Pages
Deaf
----- How To Communicate
----------------- Pages
----------------- Pages
----- Famous People
----------------- Pages
----------------- Pages
----------------- Pages


But I also have statistic & info pages related to American and Spanish Sign Language.
And also have general statistics & info pages related to "Deaf" people etc.

What will be the best SEO approach for create my sitemap structure.
BTW: I am planning on using WordPress as my web framework.

And lastly perhaps if there is some proven guidelines or basics you believe I do not understand yet - please share with me