Unfortunately, I didn't find a standalone application that you can schedule the post on multiple social media accounts. If someone already found it, I hope it will post the application soon here.
I recommend the web application which opposes the question above. You can use Buffer application, they offer you start for free. You can schedule the post as much ...
Archive Team is currently performing a large-scale archive effort on Google+ profiles. You could make a request for the profile to be backed up on their official IRC channel: irc.efnet.org #googleminus
(They also have an archiving stats overview: http://tracker.archiveteam.org/googleplus/)
I think bufferapp.com does what you want. I'm unsure about facebook promotions as that's not something I've used. It has the other features you've listed.
They have a free version, premium versions start at $50/month.