people usually buy garage door opener from sears. They have some contractors to install them. I will recommend you hire them. They are usually very professional.
If you buy a Hood fan from a store, same as sears they usually have someone do installing for them.Since they did this job many times, they usually do a good job.
If your house is new. The dishwasher pipe usually is pre-installed. The guy installs the hood fan should have enough tools to do the job. Why not ask him to do the job at same time.
Every piece of work should take a professional with good experience and right tools less than 3 hours.