as far as I can see your first question is already answered in this thread that you posted about a month ago:
In short: If you don't get a "Duldung" at the end of your asylum process, you can be deported quite quickly. And for the authorities planning to get married is not a reason to postpone the deportation.
Please specify if you did not understand the answer provided there or if you need further/other information. The community and I will try our best to help you with your question.
To answer your second question concerning the possibility of being deported with a "Duldung":
With a "Duldung" your deportation is not suspended completely - it is just postponed. That means that you could be deported as soon as the reason for the suspension of your deportation is no longer valid. In other words: yes, it could happen that you will be send back even though you are trying to get married.
Plus: as stated in the thread linked above, authorities will start investigating if your marriage is a fake marriage or not. In general it is not the authorities business to ask for the reasons why people get married, yet still they will try to find out. Especially if they are having a suspicion that people get married in order to acquire a residence permit. Unfortunately this seems to be the normal case if a German citizen and an asylum seeker try to get married.
Source (in German language): ****://***.schutzehe.***/data/de_data/de_leitfaden.htm#auf
I hope this answer was helpful to you.
Maybe @Marcel and @Steven can add some information.