Is there an option anywhere or a workaround that would allow me to check off tasks and have them still stay on the list (with a check mark nex to them)?
That's possible if the task is a sub-task. All sub-tasks stay on the list when completed unless you hold the SHIFT key when checking it off. Parent tasks won't stay on the list when you complete them.
If you want to print a list of your completed tasks, please click on the "# Completed" link in the top-right corner and then use the "Print current view" option there. You'll be able to filter the list by date, project or label before printing it.
Thanks for the quick response, David.
What I am after is to be able to print a project out and (if I select the option) have it print with the completed tasks and subtasks showing as well, giving me a global view of the project since its inception. The completed ones have a strike through or a check mark next to them so it is obvious that they are complete.
I hope the above makes sense to you.
Unfortunately, that's not possible right now, but you're welcome to vote for this request in our Votebox: http://todoist.com/Vote/showProposal/140/ and we will consider adding such feature in the future.