About project settings and settings for pdf export

Hello everyone!
I have been using CorelDraw recently and I still have a lot to learn about working with this program. I want to ask, when I make a project for a double-sided flyer (A4 format), which I will export to pdf to be printed in a printing house, what margins is it advisable for me to put (or maybe and cut marks)? And what should they be for trifold design (A4/A3)? Is there any special setting when exporting to pdf of a two-sided or trifold design?