Standing behind the imaam if there are no other muqtadis

Q: I started performing salaah with the imaam and because another person was just there, I stood behind the imaam expecting the other person to join the salaah as well. But that person went to perform wudhu and we completed the whole salaah in this manner.

1. Is my salaah valid?

2. Should I have moved forward to go to the right of imam when I felt the other person will be late?

3. Is moving forward during salah permissible and how much can one walk forward before the salaah becomes invalid?

Drinking non-alcoholic drinks

Q: Is it permissible to drink non-alcoholic drinks (0% alcohol) which have the same name as traditional alcohols and are branded similar to the original alcoholic drink. The reason I ask is because there are many of these drinks now. E.g. There is a drink called "Lager" which has the name, logo and appearance of the original alcoholic drink but is non-alcoholic.

Befriending Ahmadiyyah's and maintaining family ties with people involved in sin

Q: I have two questions: 

1. How to deal with people called Ahmadiyah? A girl was apparently wearing a hijab like Muslim women do and I grew friendly with her but now I came to know she is Ahmadiyah and not Muslim. What should I do?

2. How to deal with relatives who are involved in *gunnah e kabeera* or greatest sins. They also perform black magic and admit it. Is the prohibition of not cutting off with relatives still there for us? When these people also harm my family and try to create obstacles for every important thing.