Each business strategy is different.
1. I sketch from zero all the work starting with the keywords analysis.
2. Move to content/contexts/headlines.
3. If It's a local business that's better - go with the Google map listing which is very important. If not I skip that. and go just with Google...
Not at all. Profile creation are simply profiles created all over internet but their scope is not to brand but to gain a backlink. At least that was before Google came with the updates.
If you share your content (full article) yes duplicate. But add on your website a plugin that will share just 1-2 phrase from it on your social channels and will be safe.
Natural links aren't = quality contents distributed on relevant sites? That's what I understand from your first phrase.
Building backlinks can be considered as Spam, and your Website may face Google Penguin Penalty, instead build quality contents.
I think soon it will. Facebook users don't convert. People go there to socialize, while Google+ network is totally different. People go there with the purpose to make business!