To print a thread, you can select the "Show Printable Version" option from the "Tread Tools" in the mustard/tan colored bar at the top, above the thread body. Once you are looking at it in the printable view, there will be a link to "Show NNN post(s) from this thread on one page"
You can also select your default number of posts per page (which would then apply to all threads you read on the site) in your account settings.
Side note, this kind of question would best be posed in the Site Info & Feedback forum
, but no worries.