I started my career as a paramedic and still work as one. I worked full-time throughout nursing school
My opinion? Well, it wasn't easy, but it can be done.
The difference in certifications? For one, being a paramedic is a rather well-defined and limited, whereas nursing allows for a more varied career. You can work many different specialties and the opportunity to travel is much easier as a nurse.
The question you need to ask yourself is, which career do you want as your primary one? Do you want to work for an EMS agency or fire department? What about benefits? Retirement? What kind of work schedule? Do you plan to continue your education beyond the level of RN? There are a lot of questions to consider beyond what seems like a choice of one job over another.
The majority of paramedic programs are about 2yrs in length after becoming certified as an EMT, which would be about a year in length, possibly less depending where you do your training.
The job market? That too depends on where you get your training and who is the primary employer. In some areas of the country, EMS is under control of the fire department. Do you want to be a fire-fighter also? You might need to. In other areas EMS might be a separate service operated by local city/county government. Or, it could be provided by a private service. Of course, the benefits and working conditions vary depending on the location and employer.
Don't look strictly at dollars per hour as the deciding factor. I make more per hour as an RN, but I don't have benefits, since my other job provides them. If I took benefits from the hospital, I would make less per hour and have crappy benefits with no retirement provided by my employer. So for me, the paramedic job is the one for benefits / retirement and the nursing job is strictly for $$. This may not be right for you and your situation, but it is for me.