Due date in Youtrack

There isn't ability to add a custom field to a single issue, but only to entire project, to the each issue.

Please go to the 'Administration'  > project > fields and attach the 'Due date' there. Please look at the reference here.

Found it, thank you.
Is there a way to order issue by due date ?

Sure, please use the syntax sort by: {Due Date} or order by: {Due Date}.
If needed you can discover the search grammar in the online documentation.

Thank you Dmitry.:)