When would it become incumbent on us to actively participate in physical jihad?

Q: Please can you assist me in understanding the ruling of jihad in todays age (where we are without a caliphate) and when it would become incumbent on us to actively participate in physical jihad? I ask because I am feeling increasingly helpless when I look at the atrocities that our brothers and sisters are enduring in so many parts of the world - e.g. Palestine, Syria, Lebanon, etc. I do realise that we can make duaa to Allah (subhanahuwataála), that He ease the affairs of our brothers and sisters, and that we can make donations and offer aid in relief work. However, are we not expected to do more, by way of uniting in physical jihad - e.g. in Palestine? At which point would this become obligatory for us? Are we waiting to unite under one caliphate before doing so? Please assist me insha Allah. I have tried understanding this issue for some time now. Unfortunately, I have not been able to find the sunni fiqh of jihad in todays age. I think that there are many people in confusion, and so they turn to less reputable on-line sources to understand their role in jihad better.

Ordering someone to stop speaking to family members

Q: It has come to my father in laws attention that I have spoken to his second wife on three occasions. However now she says that I phoned her and revealed normal routine of the household. My father in law in turn took his anger on my husband and involved my husbands mother (my mother in law, the first wife). Thus resulting in emotional and verbal abuse, My questions are as follows:

I do realize my mistake was to pick up the phone and innocently respect her. Did I do wrong by adhering to the phone call? Should I prove to these inlws that I did not contact her and she phoned me? Is it right for my mother in law to order me not to communicate with any near or distant relatives of my husband saying that because she does not talk to my relatives, I should not talk to hers. My mother in law wish to not interact with me at all. Should my husband now be obligated to remove me from the household that belong to my father in law? I feel they are purposely trying to break my marriage, how does one make sabr in this circumstance?

Making others take oaths unnecessarily

Q: I asked someone to say some specific words. That Person said it in normal way but I knew it from my heart that that person was lying to me so I asked him to swear to Allah on this and I insisted many times. During our conversation that person once mentioned that my (that person's) life in this world is destroyed and you want to ruin my Akhira (world hereafter) as well. At last that person said those words with "swear to Allah". My question is now what to do? What is the Kafaarah in this situation and what are the obligations on me towards that specific incident because it was I who was insisting for this again and again. What should I do for that person?