Explanation of the hadith regarding a person traveling alone

Q: There is hadith narrated by Abdullah ibn Amr ibn al-'Aas (radhiyallahu anhu): The Messenger of Allah (ﷺ) said: A single rider is a devil, and a pair of riders are a pair of devils, but three are a company of riders. Grade: Hasan Reference: Sunan Abi Dawud 2607 In-book reference: Book 15, Hadith 131 

I travel alone for my college which is far, so what does this hadith mean?

Gifting land to one's son during one's lifetime

Q: My grandfather has several children. He had bought some pieces of land on his 3 eldest sons' names. While he was alive he sold two of the plots of land of those two sons' marriage expenditures, but kept the third plot as it is. 

Also, my grandfather did not buy land for his remaining children, but he however left behind a house without a will. 

Now, my grandfather is no more. The 3rd plot of land was bought on my father's name and is still on his name. But my father's siblings are now asking for a share in his plot of land. 

My question is whether they are entitled to any share in my father's land?

Fidyah

Q: I like to ask you about fidyah. 

1. If you can't fast in Ramadan because of ill health, do you need to give fidyah for 30 days? 

2. Do you need to give fidyah to one person or more than one persons? 

3. Can I give fidyah to a charity organisation then they may distribute it?

Brother in law and sister in law observing strict purdah

Q: I recently heard someone say that it is permissible for the sister-in-law to not make parda from her brother-in-law when: 

1. There is no scope of fitna. 

2. When it becomes difficult for her to leave her own room for basic needs. 

My friend has recently married into a family of 6. They live in a small flat. Her brother-in- law is 6 years younger than her and she claims he is an actual replica of her brother in her maternal home. There isn't a chance that they can ever be alone. It becomes difficult for her to constantly be in her cloak, burkha and pardah the entire day almost as if she is at a guests home and not in a home that she has a right to stay in. What is the ruling regarding this?

Making dua after Eid Salaah

Q: Is it permissible to make dua after the eid salah before the khutbah, thus delaying the khutbah and not making dua at all in the second khutba? 

Did Nabi Sallallahu Alaihi wa Sallam, the Sahaabah. or any of the four Imams or the fuqaha of their madhabs mention making the dua between the salah and khutbah?

Joining salaahs when travelling

Q: Is it permissible to join the salaahs when a person undertakes a journey and is a musafir? 

Example, you are leaving a country and it is zuhr time so before the flight you join Zuhr and asr? Or you visited a country and you go to a shop and maghrib time sets in so you read maghrib and Isha together? Is this permissible and if not, does one get a sin when they do it?