First off, congrats on the launch!
Will answer your questions in the order you asked:
1) All campaigns should run in conjunction with each other. Of course, your personal/company social platforms can continuously push your content out even if your paid campaigns have been exhausted for the week but in general, all of this will be happening at the same time.
2) Great question. The advice I give to this is to just start small to test the waters and see which platforms are bringing the best results and then gradually ramp up. There is not really a dollar amount to state here as everything is relative.
3) We handle the marketing for a printing company that sells B2B and currently about 90-95% of the sales are generated from inbound leads. You can check out some of the work at www.shweiki.com/blog. In regards to SEO campaigns, the SEO success has been a byproduct of the content marketing plan we implemented and continue to execute each and every week.
4) Don't really have an answer to this but don't know of any quick fix tools that will accomplish driving you up the SERPS or traffic to your site.
5) I am biased here, but I don't see how anyone could accomplish what a good marketing firm can from a cost or results perspective. Of course, there are large companies who have departments dedicated to marketing/SEO/SEM/Social etc... that can be as effective. But there is a reason marketing companies exist and it's not to give poor deals or results.
Best of luck Ajay!