Credenciel: The booklet which is needed to show you have completed the Camino. A stamp is need for every day you spend en route. You can usually get the credenciel when you arrive at one of the major starting points or you can contact your national Camino association in advance.
The individual daily stamps can be obtained from your overnight accommodation, from some churches and sometimes bars along the way. Yes, I am prepared to visit the occasional bar.
Food: The albuergues in Spain along the Camino Frances offer dinner and wine at a modest price. All along the caminos there are places offering relatively cheap Pilgrim menus - you will sometimes be asked to show your credence. If you are a vegetarian you might find yourself explaining that ham and tuna are not vegetables.
If you are a vegan there are places where you are really going to have your work cut out. You should consider purchasing stuff in the larger towns and villages and doing some of your own cooking.
Distances to cover: I cover around 20-25 kilometres a day at the beginning of my walks but it creeps up as time goes on and I often do 30 to 40 kilometres a day after week two.