Benefit of reciting Aayatul Kursi

Q: Can you please provide guidance on the benefits of reciting ayat-ul-kursi? I have been told:

1. Recite ayat-ul-kursi before going to bed.

2. Recite ayat-ul-kursi after making wudhu.

3. Recite ayat-ul-kursi after reciting your fardh salaat.

Please provide insight into the benefits of reciting ayat-ul-kursi for the above 3 occasions and also if there are any other occasions when you should recite ayat-ul-kursi.

Performing fardh salaah in a car

Q: While travelling in a car, my family prayed the obligatory namaz sitting in the car. Later I found out that sitting while being able to stand invalidates namaz. It was also raining heavily so is the prayer valid as it was done out of ignorance or should I tell my family to repeat those prayers?

If they have to repeat it, should it be prayed as qasr?

Following the law of the land that does not conform to shar`ee law

Q: I am 20 years old and live in the UK. Here we are obliged to have car insurance. Similarly, for delivering food etc. (Uber eats) we are required to have food insurance. Insurance companies don't supply that to us until we are 21, so right now, I do food delivery for Uber eats on a normal insurance. That would mean that I am not abiding by the law of the land, would that make my income haraam?

My dad is currently not working and I am paying rent for the house. Furthermore, I intend on buying another car in the next few months. If this income is haraam, when I am 21 and do the food delivery legally, but the car I use to deliver the food is from haraam money, does that make whatever I earn haraam?

If it is haraam, once I turn 21, can I repent and give the calculated amount I've earned up until I became 21, to charity? Would my income thereafter be halaal? 

Zakaat on cash buffer in a property trust

Q: A trust was formed and a property was purchased for investment purposes. Shareholders bought into the investment. A portion of the net rental are distributed to the shareholders and a portion of this net rental is held back in the trust as a cash buffer for unforseen events (e.g. Unforeseen expense). What is the zakaat implications on the cash buffer held back in the property trust?