The age of your site is a minor factor. Since there are several factors that will drive you to the top in Google, you have a great chance at ranking high with your new startup. I don't know the details of your company, but can offer you some basic guidelines. 1-follow onsite SEO best practices and ensure you new set is set up properly, 2-follow off-site SEO best practices to drive traffic to your site and build social proof, 3-run some basic PPC ads to further drive traffic to your site. I hope this helps and please don't hesitate to reach out if you have further questions!
That is now an SEO myth. You can hear Matt Cutts talk about it https://www.youtube.com/watch?v=-pnpg00FWJY
Again, the most important is your content and the backlinks. You may want to make alliances and friends with good site in a related industry with "presence" (DA) so they will link to your website and that will give you significant results. Directories are useful for that but industry related is even better.
Eg.: You in the tourism industry and the Tour Operator alliances list your site, you will have your site crawled quickly and have as much chances as an "old" site if you have good content.
In clear, do not worry about your domain age, but about the content and links to your site .. like a road to your house.
Speaking about SEO myths, that is a great list :
Hope this helps :)
Age of site itself is a relatively minor factor, if at all. What does matter, however, is site authority. Authority takes time to build and you will be disadvantaged against sites that have been building their own authority. If you aggressively pursue web marketing it can take anywhere from 6 months to a year or two to be in a relatively competitive position. That all depends on the competition. If your start up is in a relatively noncompetitive field, it won't take much time at all.
How much your site content is updated is most important. We receive about 300 pieces of new content per month. Each new piece drives a new sitemap into all the search engines, so they crawl us 4-10 times per day. We are always #1 in search priority. FYI, keywords are dead from a Marketing perspective, focus on page tags, content tags, and new content placement and site-mapping, More important is social trend and behavior management.
These are all highly automated today, knowing the behavioral engine logic, and the monetization engine logic and having them in sync is primary mission objective for today's marketing. BTW, most people do not even have a clue on these engines :)