Nanette,
In terms of your past life memories: they have been triggered, and you will find things come through your soul memories relating to this when you need the information to be there. Essentially, you had chosen to be here this time to continue your service to humanity in some form.
The man the angels spoke of you have not met yet. Don't forget 'medicine' is a huge field that also covers alternative versions as well. In fact, the field of medicine is one of the things about to change drastically on this world, when 'science' combines with 'esoteric science'.
Yes, there are spirits around you who try to get your attention. It the way Spirit works to 'wake up' someone who is a natural Sensitive. They see your (as yet sleeping) spiritual awareness like a light that you radiate, which attracts them. This is something that will probably always happen with you and it's perfectly natural.
You don't have to train if you don't wish to, as you'll find that sort of thing comes naturally once you focus on it. Such a gift remains with you whether you use it or not. There is always a choice. You may initially wish to seek out others who work as Spirit Mediums, or whom help others develop their gifts. It would be good for you to see how others work with such things (both the good and the bad) and come to your own conclusions.
There is always the choice to use such an ability to help others, but it's not a prerequiste- since you are in charge of your own destiny - but it can also be a powerful tool for you to use in your own life as you learn to listen to, and follow, your intuitive guidance and your inner senses.