You may have a little more than 200 worksheets in a workbook. Take note that by default, Excel will show up to 3 worksheets but you can always add more tabs depending on your needs. Do take note that the more tabs that you place, the harder the file can be saved especially if you would be placing a lot of graphs, charts, and so much more.
Each header and footer can hold up to 255 characters. You may need to make some adjustments if in case you need more than 255 characters. Some people complain that they do not get enough worksheets. This will depend on the memory that your gadget has.