Cash is the way to go with all of the small stores. ATMs are common in all towns. If you are looking to purchase TAX FREE, you have to get the paperwork at the time of purchase. Doing the paperwork is at the discretion of the shop keeper. Most of the stores, but not all, also carry extensive needlework supplies.
Hours conform to Germany store closing laws.
They are not open on Sundays. Evening hours are normally only on Thursday. Most stores have Saturday morning hours, but this is not a given. They are located in many areas in Germany. In the warehouses you can make cheap finds.