If you use wordpress then yes you can definitely create a feed and directly post it to facebook. There are quite a number of plugins / auto post options available for posting to facebook as soon as an entry is created. Auto tweet is also possbile.
With regards Google Plus as far as I am aware currently API does not support auto posting. There were talks that the new API would include facility for auto posting, but I have no idea whether it has been made available or not.
If you let me know the ecom component you are using I can suggest plugins for auto tweet / auto post to facebook.
And for your reference, one simple and easy way is to add your feed to feedburner and then select auto post and that will do the needful. That would be the easiest option for you