Hello, Dr. Chen

I heared that after 18 months with Niederlassunsbewilligung (schluessercraft), a person can apply for a one-year visa and work everywhere inside of Vienna (not outside of Vienna). Then, is it possible for a person himself to open a small shop or a company for some business with this new visa? After 5 years starting from getting Niederlassunsbewilligung, can this person apply for 5-year long-term visa?

Thanks a lot!