There is no hard and fast rule, it all depends. It may take between 6 months to 12 months to see any significant changes in ranking generally. In Google TT search where it’s not as competitive, especially visible in results where there are directory or yellow pages results, Facebook pages, etc., i.e. no actual websites, the chances for success are much quicker.

No, nothing can be promised except that the hard work that is required goes in. As the saying goes Garbage In, Garbage Out, and we don’t put in garbage.

Sponsored searches can be used until your site appears on the first page of Google. With a sponsored serch you pay to appear at the top of search, but with the ‘Ad’ badge to inform visitors that your appearance at the top is not organic.

For the moment it’s Google only as it makes the most sense obviously. There is little need to optimize for other search engines specifically. As long as you apply proper SEO best practices a good search result should follow.