Need your opinion - which printing method and how to protect designs from printer?

I am working on someday being able to print my own shirts but for now I have a design that I want to print out. The design is basically black and white but has gray shadings.

Knowing this; what are my options in regards to printing this on a shirt? Should I use heat press or screen print? What would you use?

Also, is there a way for me to protect my design? How would I protect my design from a printer that might want to print a few shirts for himself?

Thanks in advance!