Editing tips and suggestions

I like to think that I am somewhat good at writing. I enjoy doing it as a hobby and it is something I am passionate about in my leisure. I keep reading my writing and referencing the technical aspects of my work and I feel way less confident now that I have committed to creating a work I hope to get published. I have taken a boat load of writing classes but all of them around academia and technical writing and very few around just writing fiction so I am going into this having to teach myself. Which leads me to: Can I hire someone to review my work and make notes about my errors or how to improve areas. Is that what an editor would do? My second question is how would I also protect my work. I am not tooting my own horn and I can't say there probably haven't been books that have been there or done that in the genre that I am writing but if I did find someone to review my work, how would I share it but also protect it so that it would not be stolen essentially. Any advice is welcome.