Postgres Licensing

May be this is the wrong place to ask the question. Still, answer me if someone can or please redirect me to some place
whereit can be answered. My questions are:<br /><br />1. PostgreSQL can be distributed freely according to the license
terms.Can it be sold (for a price) without changing anything in the source?<br /><br />2. Does the license restrict me
fromadding my closed source additions to the project and then sell the product? I want to add in a few files here and
therewhich would be closed source in nature, while all the changes made to the original files will be open, and then
sellthe modified database with a dual license. Is this possible? <br /><br />May be you guys are hard core OSS
enthusiastsand may flame me. I request not to and please consider my question. <br /><br />Thanks a lot.<br /><br />