Tipping

I`m not sure who is to be tipped...the dj, limo driver, photographer? What if these people are the owners of the business, and not employees of the company? Should they still expect a tip? And are we expected to provide a meal at the reception for the dj and the photographer (and videographer)? At $50/plate including bar service, this adds a fair amount to what will already be costly services, but I`ve been told by others that I should include these people in my final head count for the hall. Doesn`t seem right...they are hired to perform a service at the reception, they are not guests. Opinions?