Go here, click on the links that lazersteve gives and start reading. These links will specifically answer all your questions, 100 times over:
http://goldrefiningforum.com/phpBB3/viewtopic.php?f=60&t=5604
Use the link that leavemealone gave above and download the Hoke book - the download is free. Although it is mainly for jewelry scrap, it is the best source for learning the basics of working with many of the chemicals.
Your questions are way too broad. Do some reading and then you will have more specific questions. There are no shortcuts to learning this and everyone has to go through it. I know it seems overwhelming but, if you first spend a week, or two, reading, you'll soon catch on.