We have set up a page for this site on Facebook
Many people have Facebook accounts, in fact many into this lifestyle have one for family and friends and another for swinging, hitting the Like here is just a vote for this site on Facebook and has nothing to do with privacy, photos or similar and the Like/share bits don't appear in places on profile pages or similar, those that don't wish to click on Like do not have to, but there will be those that do and that will help the site.
Its actually no different to having a link back to here from another site, of course only those with a private facebook account would be likely to click on Like.
We have had links like this on our Australian site http://www.swingersheaven.com.au/ for years and nobody has had any issues with them at all.
The fact of the matter is that having Facebook/G+ likes helps the site to rank better as it provides social signals to the Google and other search engines.
Its not that Facebook is on swing4ireland, its more a case that those who want to can spread swing4ireland to their mates on Facebook if they wish and for those that do use Facebook a lot can keep up to date with things that we post on the Facebook page we have.
Ive noticed recently that people I know from s4i are popping up on my "people you may know" section of Facebook. This bothers me as I dont like aspects of my private life being known by my swing side of life...