I was doing MPH work when I interviewed for medical school and I found that my interviewers WERE impressed with the fact that I pursued public health and mentioned that it would be nice if more doctors had public health training. Most of my interview questions rotated around my coursework in the masters program and my view on how my background in public health would help me as a doctor. They seemed to believe that the MPH is a valuable background to have considering medicine and public health are closely related. One just views the health of the whole whereas the other views health of individuals. Wouldn't understanding one help with the understanding of the other? I digress, but the point is I don't think it would hurt you and in my case it helped out a big deal.
If you do this as a stepping stone for medical school, I wouldn't prance around saying "I'm doing this only as a way to boost my med school application" as many of my classmates did. They were looked down upon in the masters program because this made it seem like they didn't care about the degree and the public health principles at all. Also, med schools don't like to pull students who've started other programs and don't intend to finish them. If you truly believe in the value that you can gain from the program and when you apply and interview it comes across that you do, this may make you stand apart from others. Although it may be padding, you're also learning so much about the health system we will have to deal with as doctors.
As for jobs, I agree that the pay will not be the greatest (considering you will have had a masters). I also agree that most of the jobs that my friends who've graduated and are now working or are looking for work have similar starting salaries as those students who've graduated from undergrad. depending on what type of concentration you choose to do will also affect your job qualifications, job salaries and job demand of agencies/organizations/companies. From what i've heard, epidemiologists are the highest in demand. Community health/social behavioral health/program planning fields pay less. Emplyment that alumni from my school have taken on consist of: working for the CDC, health departments, not-for-profit organizations, hospital administration (including hospital CEO), research and etc. If you think that there's a chance that you might have to take a job in public health, you have to make sure that this is something that you are really passionate for. I've known people who've done this for the sole reason to get into medical school and then didnt...they are now completely unhappy with what job the MPH has lead them to. I've known people who thought they were wanting to go to medical school and realized that this is their passion and are completely ecstatic to be involved in public health.
As for the GRE, I'm not sure which schools don't and which schools do accept them, but if it comes down to schools you want that REQUIRE GRE scores, just take it. It's NOT THAT BAD! Come on - you remember the MCAT right? Well, it's about 1/10 as stressful as that. If you survived the MCAT, I'm sure you'll survive this too.
Anyway, that's my .02. Hope it's helped out. Best of luck!