@Ale113I usually try to fulfill their needs if it is not too much for me. If the ingredients they ask for are the same price I would change them for those guests. They have the adress when they book so I don't know why they ask for that. I wouldn't buy them sunscreen but I would write a list of the closest supermarkets where they can buy one. Each request is different and I take it individually. Do as you feel, try to accommodate them but don't try too hard. They need to know that everything extra is a favor to them and they should appreciate and not take for granted.
Like Ana I always try to adjust to the guests needs.
The food would be something I would try and do for them. Giving them my address for mail or insurance would be something I discouraged. But if they look they already have it.
For thing like sunscreen and bug repellent I direct them to the nearest store.