A travel clinic should be able to identify the specific entry rules for each country for you. As for getting the vaccine, I think it depends on the relative risk depending on where you are going and what you are doing. If you going to stay in nice hotels and take guided tours, your risk is much less than if you are camping or hopping from place to place on your own. The risks depend mostly on the trip you are taking.
When my husband and I went to Africa, I did not get the yellow fever vaccine, but that was just for our trip. The travel clinic gave me a card with the excemption signed by the doctor at the clinic.