Divorcing one's wife while living in another country

Q:

1. I need to issue a divorce to my wife but she is in my home country and I am abroad, can it be done via video call?

2. If I say it 3 times is it a valid and will the divorce be final ?

3. She has 2 kids from a previous marriage (their father is no longer in their life), after divorce, do I have any rights to the children who are not biologically mine? If so what are my rights?

4. Please advise me on the correct way to issue the divorce to my wife who is living in a different country since I do not have the means to go home to do it.

Suspending talaaq

Q: I told my wife that if she talked with her family members on her mobile except her mother and father then she will be divorced. If in case she talked to anyone then what will be the situation? Will she be divorced? I said only once talaaq in case she talked with them on the mobile.

Yawning in salaah

Q:

1. I covered my mouth with my hand when I was yawning during salah but quickly put my hand down.

2. The next time I yawned I believe I just stopped reciting and let it happen.

3. In another salah, I yawned, however I continued reciting as I yawned.

Are my salah’s fine?

What should I do if I yawn in salah?

Second jamaat

Q:

1. There is a masjid inside a university where many Muslim students live, but it often does not have any jamaat on Sundays, though Friday prayer is held there. An imam is appointed for the masjid, but he often does not come for fajr, isha and prayers on weekends (maybe because he lives far from the university). Is it correct to start a 2nd jamaat after the imam has already led the 1st jamaat in Salaah?

2. Is it correct to offer Friday prayer in this mosque?

3. I led a 2nd jamaat in this masjid, but after I started, I heard someone else leading another jamaat in the corner of the masjid. I did not know this before I started. Will I and my muqtadi's have to repeat the Salaah?