1. I am sorry but presently there is very little documentation available, however I can help you with your queries.
2. You need not add anything for random quote module. By default it will display the random quote. If randomness will be more visible if you have more number of quotes.
3. Do not put anything in quote id field if you want to load random quotes. If you want only same quote load everytime, then only enter quote id in that box.
4. Presently module does not support entering category id. I am adding that field to the module. Please drop an email through contact us form, so that I can send you the file.