I have some similar terms, though I tend to ask 1/2 payment up front (except for expensive and long commission where I use to ask only 1/3) I also agree with Jack that the exact details of the product delivered should be mentioned in the form, whatever the one you use. As for the rights given, many people (clients and artists) tend to forget that a specific license with some commercial use or a full copyright assignment should increase the price of the commission (and those exacts terms of rights have to be detailed in the form used, since ther can be many different ways to assign some commercial rights for instance).