In GSA edit the project and on the Project Data/Where to Submit section, right click and select "uncheck engines that use no contextual links". That is all that is needed.
I have not used Ultimate Demon and I personally am not sure if it provides the kind of quality site links I would prefer. I had purchased Bookmarking Demon several years ago IIRC and I applied for a refund immediately as almost every site there was low quality pligg and scuttle sites which are found even in normal all in one tools such as GSA SER. However, things might have changed now and they have a free trial with money back guarantee if you do not like it.
Turbo Web 2.0 has lesser platforms right now but the developer has been maintaining it and improving it with time. There is a script builder in Turbo Web 2.0 which can be used to build more unique scripts too though I have not tried it personally. FCS is a better bet for the sole reason that it is web based and so, there are lesser chances of facing problems. However, most people I have spoken too mention that you need good quality proxies in FCS too for the best results. The default proxies they use are not that good in terms of success rate if I am not incorrect.
Personally I would probably go with FCS networker or Turbo Web 2.0 instead of serengines if I were you. You can check the official thread for serengines at the GSA forum and there are people who mention that they fail to get even a dozen platforms working at times. In comparision, FCS or Turbo Web 2.0 easily gives around 2-3 times that with good quality proxies.
For proxies, buyproxies is good but there are lot of providers out here in the marketplace which you can check too. Most of the providers here in the marketplace with good reviews would work well with almost every Web 2.0.
And just to remove the confusion, FCS does not support every social site out there including Facebook. They used to make the currently working sites publicly available in the past in this link:
http://www.fcsnetworker.com/supported/supportedsites.php
I was using that to check the platforms between FCS and Turbo Web 2.0. But they have removed that link now. So, there is no way to check the current list of sites. That definitely did not include facebook. In fact, there are hardly 2 or so facebook management/posters out there and they are a lot more expensive. There were a few social bookmarking sites too in that list if I remember correctly. Overall the quality and collection of sites both in FCS and Turbo are far better than most others.