The use of Facebook for business, is as a soft presence. The content should be a mix of business, corporate philospy and community engagement. Having a FB page also allows you to "like" your clients/prospects pages. As most folks will "like" in return, this gives you a quiet platform for your message and also a look into that business. The information gathered there can be useful when practicing more traditional business developement methods. Also, though you stated you aren't planning on purchasing advertising, I have found FB ads to be very cost effective and effective in general to promote awareness. Facebook is also great at compiling the "review" data. You'll know for every post how many and who have seen it. That is definately helpful in deciding your marketing content.