Ways that friction are beneficial:
Standing - Friction allows you to stay in position instead of moving around even when you do not want to
Braking of cars - Similarly, friction makes it possible to make a car stop
Ways that friction is nuisance:
Wear and tear - Friction produces heat, which would flatten shoe soles, smoothing the gears or other mechanics in machineries
Yes, friction always exists.
Yes, friction is a force that always acts opposite to the direction of motion.
Yes, the coefficient of static friction is always higher than the coefficient of sliding friction.
Yes
Yes. Friction is always a factor. It is partly through drag, which can be thought of as friction, that the wind in a tornado is able to cause damage.
benificial effect
Since you are ill, it would be benificial for you to have a rest.A teaspoon of honey a day is very benificial for your health.Name me three fruits that are benificial for you?Something that is benificial is good for you.
yes
yes
no limiting friction is not less than rolling friction
Friction's direction is always against the direction work is being applied to.