Naming directories & web pages

[shallow]

I'm redoing my website to utilize a Content Management System. The original site was started about three years ago. At the time the best thinking was to give very descriptive names, or phrases, to directories and web pages. I've been told this has changed.

What is the maximum number of words to use for a directory name? If there are pages in the directory other than an index page, what is the maximum number of words that should be used? Should I use dashes or underscores? I'm currently using dashes. Also, am I correct in thinking that the title page and description are more important than how an HTML page is named?

Besides the cost, this is going to be a time consuming task and I really do want to get it right. Thanks in advance for any help you can provide.

[shallow]

Still hoping to get some responses to my question!

For example, am I likely to attract a penalty for using something like:

example.com/keyword-otherkeyword-widget-directory/keyword-widgets-and-keword2-wodgets.html