A: The easiest way is to find something and document it. Also check the unmaintained HOWTOs and see if there is a subject there that you know about and can continue documenting.
A: Please see http://www.tldp.org/manifesto.html#pub for more information about publishing LDP documents.
A: Contact the author of the document, or the LDP coordinator at <email@example.com> and mention the problem and how you think it needs to be fixed.
A: That's okay. You have the option of writing your first draft of the HOWTO in the format of your choice, then submit that to the LDP. An LDP volunteer will review the document, then convert it into DocBook for you. Once that's done,it will be easier for you to maintain the HOWTO. If you have questions, you can always drop a line to the LDP volunteer or the LDP Docbook list at <firstname.lastname@example.org>.