batt good could not jump. suspect clutch starter or solenoid. don"t think starter ?

my coolant leaks a little each time my engine gets turned off and i want to try stop leak...i think i put it in the coolant reservoir..

leak happens when engine is off...and not too bad, but i want to try stop leak

I've been trying to figure out why this car makes so much noise at low speeds and when I stop at intersections. It sounds like it's idling high, but this only happens when accelerating and while sitting at an intersection. And it stops when I take my foot off the gas or put the car in neutral. Any ideas?

about two weeks ago, I took my car for a car wash. When I turned the car on and shut the doors my seat belts engaged like normal. Then I pulled away and they disengaged, sliding back and forth. Now they are in the open position jolting back and forth not sliding. I had to unlatch the belts cause they wont close. Every now and then the passenger belt does slide back and forth. What does this mean? How can I fix this problem?