Can it be written entirely by myself (never got legal training) following the examples of my competitors? If not, is it worth writing it myself and then asking a lawyer to review? Thanks!
There are a lot of samples of TOS and Privacy documents on http://www.docracy.com/
Many of these are from popular sites. My suggestion would be to find one that covers most of what you are looking for, then run it by an attorney to make sure it's legal and covers you the way you expect. This saves you the money of having a lawyer to draft the entire document for you.