Is it true that the german rulers depended on the personal loyalty of their warriors
but the rulers must also have their way to make their warriors loyal, i guess they had to set up the rules and obey the rules in person, otherwise it should be very hard for the warriors to be loyal to them.
It's true that the German rulers depended on the personal loyalty of their warriors. This loyalty was the one that made the rulers to have more power to act on.
Yes. Assassination was always a possibility. Another reason is your army is your discipline arm, so you can't have them questioning you.