Thank you for your answers. I didn't want to neuter him because of the reasons I listed above. My husband, however, wants him neutered. I don't know whether he did it because of an accident or marking, but I believe it was an accident.
I guess we shouldn't have scolded him, but since then he is still peeing outside rather confidently.
However, I just took him outside for his morning walk and after we were finished, we came back in and he continued to whine. That was unusual behaviour for him. It was a real long walk this morning and by the time I brought him back up, he was 'dry' from peeing.
Other than that, his behaviour and eating habits are fine.