There will be facts, dates and information within your subject area that is considered common knowledge and as such you do not need to reference this. If you are not sure think about whether you knew the information before you started the course - would you expect other students to know it? If you are unsure then it is better to reference than not.
Some sources will be written by multiple authors if there are 4 or more then you would use et al. List the first surname followed by et al. You will need to include all the authors in your reference list/bibliography.
The first thing you should try to do is find the original source of the information so that you can quote directly. This will enable you to check that the source that you are reading is representing the original idea correctly. Sometimes however this will not always be possible so you will need to cite both sources within your in text reference. List the author(s) and use the phrase 'quoted in' or 'cited in'. Your bibliography will only include the book you have read.
Unless your assignment or lecturer explicitly states how many references you need there is no exact answer to this question. It will depend on the type of assignment you are doing, your word count and the amount of reading you have done. If you are struggling with knowing how many references are suitable ask advice from whoever set or is marking the assignment.
Try to avoid using lots of quotes and think about whether these you need the exact wording. Short direct quotation (up to three lines) will be included in the body of your text but need to be enclosed in quotation marks. Longer quotations don't require quotation mark, instead these are marked by entering as a separate paragraph and indented from the main text.