[Course Press PRO] Basic Certificate and Progress Doesn't Show

Hi, I would like to know how can I manage basic certificate on my courses:
1 problem: I cannot see a preview of it (so I don'yt know whether an image upload does have sense or not
2 problem: It seems that a progress is approximative: I've tried on completing all the units and it won't show as complete on some of them (it'0% on some, 83 on others or 73% - and I think all of the units follow the same publishing system)
3 problem: can i make so that people automatically download a certificate without a progress / completion?

Thank you!