Can a Muslim Do Business with a Non-Muslim?

He bought a piece of land, then he found out that it had been seized by force from public property

Is he sinning if he rides the bus standing, because the rules do not allow that?

He is paying money and will get an apartment in five years’ time

There is a piece of land that the owner left behind when he travelled forty years ago; is it permissible to remediate it and make use of it?

He buys goods when they are available and plentiful, and sells them when the prices rise. Is this hoarding or profiteering?

Is it permissible to seek the help of someone else to review his master’s thesis from a linguistic point of view?

Is it permissible for the business owner to install surveillance cameras without the knowledge of his employees?

Ruling on decisions made by a sick person when he is drifting in and out of consciousness

Ruling on using someone else’s belongings without asking him for permission, when you know that he would agree to that