I have been a professional videographer for over 20 years. My thoughts on your question are as follows: the Sony pxw-fs7 is a very expensive and complicated camera for someone "starting out" in the video field. An important thing to remember is that the quality of the CAMERA does not make the video – the quality and experience of the VIDEOGRAPHER (and video editor) is what makes the video.
My suggestion would be to purchase a much less expensive HD cam and use it for a few weddings (for free) until you become familiar with what is required to handle all the details of professionally filming a complete wedding. You will find the process is quite different than shooting still photography of the same wedding. Once you feel comfortable with the process and with your edited work, only then would I consider purchasing a camera such as this (much less a crane!). Good luck in your new endeavor.