Performing fardh hajj or sending one's parents for umrah

Q: My husband and I wanted to do hajj in 2022. We have been waiting for this for three years.

When he was first time eligible for hajj, he sent his parents for hajj to get the reward and to give them a chance first. Due to the pandemic we were not able to go, now we want to go but his parents want him to send them for umrah.

What should we do now, give preference to his parents nafil umrah or to our mandatory hajj? 

Performing salaah while on the aeroplane

Q:

1. If I am travelling on an aeroplane, and the salaah time enters, then what is the correct way of performing salaah and what timing do I follow for each salaah?

2. If there is not enough space to perform salaah due to the aircraft being small, or the airline does not allow me to stand and perform salaah, will it suffice for me to sit in my seat and perform my fardh salaah?  

Having a Quraan khatam once a year for the deceased

Q: My in laws have a culture of performing Quraan khatam once a year for the deceased by having someone or a group reading Quraan and send esaale sawaab to the deceased father or Muslim family members. There is also intermingling of opposite sexes at the event. Cooking etc. and feeding the guests.

My question is, are all those efforts counted in the court of Allah, such as Quran tilwawat, dua for the deceased etc., whilst there is no pardah between the opposite sexes, intermingling etc. at those gatherings?

Being a witness to signing for a home loan bond

Q: I was traveling with a co-worker who stopped at the attorney offices and asked me to come inside with her. When I went inside I was asked to be a witness on signing for a home loan bond that was taken with the bank.

I am feeling very uneasy and I would like to find out if I have committed a sin by being a witness to the interest stipulated on the contract.

Can I somehow get my name removed from that contract as I myself try my utmost to not deal with interest bearing loans. 

Imaan is a precondition for Jannat

Q: If my non Muslim neighbour passed away and me as a Muslim assume that this person is going to jahannam forever and ever and ever. Then there is a hadith about a prostitute who gave a thirsty dog water to drink and she was granted entry into jannat. So is it right for me to think that the non Muslim neighbour is going to jahannam?