welcome to the forum!! i hope you stick around - there is more than enough info in here, and helpful people to share, you'll be a droid master in no time! i would encourage you to browse thru the Droid Discussions and Droid Apps sections, and then journey over to the separate section devoted entirely to the DX.
as for your question about the droid forums app, just press the menu key when you are in the forum or thread, and select "new topic" (to start a thread) or "reply" (to post in an existing thread.
Welcome to the forum. We have a section dedicated to the X, you should check it out. I believe there are others there that have had battery life issues as well and may have some input to your question. To get there hit the Forum tab at the top of the page and scroll down until you see the Droid X sections.