Can I switch careers after getting my green card?

My I-485 was approved and waiting for 180 days until I do anything. First the reason why I want to quit my job is because my manager has anger management issues and has created a hostile environment - this started pretty recently. Also I wanted to add that my GC process didn't start until I was with this company for 2 years. My question is: 1) Can I quit around 6 months and take time off? With the job market right now (actively looking), I can seem to find any other employment but I just want to leave the current company. I will not be seeking public assistance as I can support myself for a few years. 2) My PERM application was so specific about this job that the same job is difficult to find. Can I apply for jobs that I am qualified for but not same as what I was sponsored for?