Editing one's pay slip to get a better salary

Q: I am working in a company in night shifts and I am planning to switch to another company due to salary concerns. To get a higher salary I have edited the payslip of my company's current salary because most of our collegues and I feel that the companies are exploiting us by paying us a less salary and they are getting higher profits. I feel like it is cheating because I am editing my current salary from 17000 and faking it to 21000. I have already been selected and if I join that company, is my income Halal or Haram?

Getting a fixed retainer on one's teeth

Q: Do you think I can get a fixed (permanent) retainer as opposed to a plastic retainer for my teeth which I can get off and on, just for the simple reason that I feel like a plastic retainer which you take on and off and have to possibly wear forever, will be a nuisance? There have been cases where not wearing your retainer will result in your teeth shifting, which would be a huge waste of money that was spent on braces. I feel like a fixed retainer will be easier for me.

How should a Musaafir calculate if he has to perform full salaah or qasr salaah?

Q: How can I calculate 15 days during a journey in order to know whether I need to perform qasar Salaah or full salaah. Suppose I reach a destination on 1st Dec 05:30 pm and plan to stay till 15th Dec 05:30 am.

Do I need to to take into account till 15th Dec 5:30 pm (360 hrs) as it is less than 360 I should offer Qasr even though it is 15th day ?

Making a promise to fast if one's wish is fulfilled

Q: I had promised Allah Ta'ala that if He blesses my sister with a child when she was unable to conceive, I will keep 7 fasts for Him.

I even promised Allah Ta'ala to fast for two more reasons which He accepted and fullfilled.

I owe a total of 9 fasts for many years. I am trying but I am unable to do fast. Is there anything which I can do easily instead of keeping 9 fasts? I don't want to upset my Allah Ta'ala as He has done so much for me.