Firstly, when starting any project, you must consider whether you have enough budget, staff and time to pull it off successfully. Do not think of launching a social media strategy as a quick and simple once-off process: after the initial investment, your profiles, blogs, pages and feeds must be maintained and kept up to date.
That's correct. It is neither a quick process or an easy one. You need to know your audience well but firstly you need to find the audience. You have to know what you want to sell or present. Know the strengths of your product or project and the vices. Having clear idea what you want and who you want to sell it to is just a first step. You can't just have a social media account. It needs to be constantly improved and worked on via adding more content.
I got 100% sales from Google and other search engines without using social networks 1 year back. I think social media can help a bit but no more, just focus on SEO and it will bring more benefits to you.