I take sleeping pills because I can't go to sleep due to stress from work. Am I going to be addicted to it?

Maybe. Sleep aids are at times necessary to overcome short term insomnia. However, you may run into a psychological dependency once sleep aids are chronically taken. I recommend to address stress management. Cognitive behavior therapy with relaxation, stimulus control and other is a healthier way to overcome the insomnia.
Yes. Anything that creates a routine will also create disruption eventually. Also things that alters brain chemistry is the hardest thing to correct in life.