money as debt

It would seem natural, that money is created by the State, and in fact most Central Banks seem to be owned by the State and run by it. I say "seem" because, to all intents and purposes, it is an apparency. They are almost constituting a "fourth power" in addition to the three legally constituted and well known "traditional" powers, legislative, executive and judicial.
When the State needs money, it does not order the Central Bank to credit some money to the treasury’s account. The State has only two ways to obtain money. One is taxation of it's citizens, the other is borrowing from the banks.
When the Central Bank issues money, this is done in the form of a loan. The State has to borrow this money, and must promise to repay it, with interest. The same is true of course for a private person who needs money borrowing from a commercial bank. The bank is happy to loan, as long as you can show you have security, and promise to repay with interest. The banks are essentially creating money. Banknotes, when they are printed, are considered the property of the Central Bank. They are not given to the State to spend, but are brought into circulation against a corresponding debt. Anyone wanting some of those notes to spend, has to "buy" them by giving up some of their credit. And in any case, most of the money in circulation (more than 90% according to the video) is not banknotes but "credit". When you go to your bank asking for money, the loan you get is created right there in your bank. The "money" consists of figures on your bank account, and it can be spent writing checks, giving an order to transfer or drawing the cash. Banks only have to have a small percentage of their loaned-out money actually available. The rest can be paid out just by moving some figures from one account to another. Money is created just by inserting some numbers into a computer.

2. Why create money as debt? Why not create money that circulates permanently and does not have to be perpetually re-borrowed in interest in order to exist?

An economy needs money so that goods and services can be exchanged. If there is too little money goods will remain unsold, prices will fall and we call this deflation. If the scarcity of money becomes serious, eventually the economy will go into recession, that is, production comes to a halt, people lose their jobs, misery starts to reign. So it is very important that the amount of money in circulation is at all times sufficient for people to buy the goods and services that are being offered. If on the other hand, too much money is available, inflation, which is a general rise in prices that diminishes the "buying power" of money, is the result. Inflation is as undesirable as deflation, and it would be best if money were stable in it's buying power.
At this time, government has only indirect means, to assure such stability, because it is the banks who can determine how much credit to create.
Also with the government unable to create it’s own money, the only way to make sure there is enough money to buy the goods that are on offer, is to continue taking loans! Of course that means to continue to pay interest! That is why governments never have enough money, and why we have to be taxed to the limit of endurance to pay for debt service, in addition to all other government expenditures