The best thing is to be very specific and tell the sitter what your expectations are, regarding the home and the pet. For instance, You may ask the selected sitter if they will / to please bring their own food/ beverage, or some pet owners will specify items such as “you can have this fresh fruit that is on the counter or these fresh vegetables in this bin, or this basket of snacks, etc.” Along those lines, you probably want to specify anything that is hands off or OK to use. Examples of that are a: Wi-Fi password, coffee maker and other such appliances, certain rooms (i.e. which bed/bathroom), etc.
Likewise, if it’s important that your dog is on a certain routine, communicate that clearly.
I don’t think you are obligated to provide food for the pet sitter. However, I’ve read some sitters act differently than I do and literally help themselves to whatever they want in someone else’s home. For three days, I think they should be able to bring their food and beverage with them. However some people might counter that they’ll go out for meals and leave pets unattended then, so it’s a good idea to discuss.