Taking oaths that one will become a kafir if something is done

Q: Some scholars say that if a person takes an oath saying “If I do this or do not do this, I will become a Kafir forever”. This would not necessarily result in that individual becoming a disbeliever upon the performance/non-performance of that act. The person only becomes a kafir if he or she swore the oath with the belief that he or she would adopt kufr upon its non-fulfillment. Is this true? 

Halaalah with an impotent person

Q: Me and my wife love each other, but due to some misunderstanding 3 talaq occurred between us. We did not know about three talaqs but I uttered 7 to 8 times the word talaq to her. So people said that it is 3 talaqs. We do not want to separate and we do not want to break the laws of Allah so we were told about Halalah. Some friends suggested this to us. Since one person is impotent eunuch and has sympathy for us, he would like to help us if Shariah permits.

Accepting the proposal of a boy who sells CCTV and DJ equipment

Q: A man proposes for a woman, and both are satisfied with the proposal. He has a business where he sells equipment as a living, primarily CCTV camera systems. He has also sold DJ equipment (exact details are not known) on 2 occasions. My questions are as follows:

1. Is the selling of CCTV camera systems permissible?

2. Is the selling of DJ equipment permissible?

3. Is his income halal, and would it be permissible for the woman to go ahead and accept his proposal?