You will not be competitive as an EMT applying to a PA program that requires prior health care experience. Most other applicants will be RRTs, RNs, Rad techs, paramedics, etc. Better to go through EMT and Paramedic before applying to PA school. That said, there is an increasing amount of PA schools that no longer require HCE.
While 46Young makes an excellent point, I generally subscribe to Daedalus' theory. And in the military, I've spent a lot of time working with a lot of PAs from every area of the country.
It is going to be variable from school to school. The origin of PA schools was to take seasoned healthcare professionals, who had a good working understanding of patient care, and a proven aptitude for healthcare, and transition them into mid-level providers. In fact, it was originally started utilising military medics. But, as Daedalus says, many schools are no longer working under that original theory anymore. I have worked with several PAs who went straight from college to PA school without ever wasting any time driving an ambulance. The results have been as mixed as those of PAs with experience, so I can't really draw any solid conclusions yet about the difference this makes.
The thing about finding out for sure if you are really cut out for healthcare is probably the most important aspect of prior experience. You'd hate to bust your arse on a pretty difficult Bachelors Degree just to get into PA school and find out that you don't really like smelly, incontinent, crying, dying people after all. That is the primary reason why becoming an EMT or medic may be a good idea. Thing is, becoming a medic takes as long as becoming an RN these days. And I don't know where you are, but the paramedic job market is in the toilet across much of the country right now, so you may not even end up getting the experience you are hoping to. For that reason, I would strongly suggest that you get an Associates in nursing first, so you can actually make a guaranteed good living while you complete the next two years of college pre-requisites to get into PA school.
Do the research. Contact some PA schools and find out what their admissions criteria are. Find out what percentage of their incoming freshmen have healthcare experience and how many do not, and what their preference is. If the chances look good that you can get into a school without healthcare experience, then that is the route I would go. It will be faster, and allow you to better focus on your Bachelors education without being jerked around by EMS nonsense.
I certainly would not quit your current job to do EMS. College is too expensive, and EMS pays too little, not to mention that EMS shifts (usually 12 or 24 hours long) are very hostile to a full-time college schedule. But, if you can stay focused on the goal, and not get sidetracked by the song of the siren, it would not otherwise hurt to become an EMT (after all, it's just a couple weeks of night school) and do some part-time ambulance work to get your feet wet. It's not even necessary that it be actual emergency work (which is hard for most EMTs to ever get). Any patient exposure is going to be helpful to you in beginning to think as a caregiver.
Good luck!
