At 66 years young, you are in the prime of your life for becomming a pilgrim.
I don't think a cell phone is needed if you are walking in spain because there are lots of albergues (hostels) on route. On a couple occasions, I've had to walk an extra hour to the next village to find a bed, but this is no great hardship. Making reservations along the way is not necessary in Spain. France however, is another issue. I haven't walked any of the 3 or 4 routes in France that converge in Spain, but pilgrims I know have told me that they carry a cell phone and make reservations a day or two in advance.
Spain has a good public health system, and when I went to see a Doctor for a minor ailment, he didn't want my money, asking, instead, for me to pray for him in Santiago. However, should the unthinkable happen and you need to be hospitalized, travel insurance is worth having. It only costs me about $ 2.00 per day so is cheap peace of mind.
Enjoy the dreaming and planning for your Camino. And do lots of walking ahead of time with your loaded backpack to become accustomed to carrying the load.
Buen Camino,
David, Victoria, Canada.