Except for pay-for-placement advertising, no one, except the search engines themselves can guarantee top positions. There are myriad factors that go into the calculation of a position on search engines and they all vary from day to day.
As a direct result of the factors above, search engine positions are also like the stock exchange. They are ultimately decided by players beyond our control as web developers. New pages with original, unique content are added daily on the website and outdated ones are deleted at the same time. This, along with many other factors create a fluid environment in which websites work in.
This is another magical wonder product from the land of search engine spammers united. The cultivation of a link's popularity takes time and dedication. Even if a spammer gets your website in the top ten, this is short lived because as soon as the search engine programmers find out, they kick your website out.
Your website should always be in flux. The internet is always changing - new technologies are being developed, new browsers are being created and more. On top of being compatible, your website needs to be relevant. Having a website with 2003 news paints your firm in unfavourable light as it looks like you're not interested in keeping your online clients informed.
Content always will need to be tweaked to achieve the best possible search engine ranking. With information gathered from analytics software, you can tweak your content to ensure that the keywords you use are the most popular for your field.
First and foremost, the notion that there are thousands of search engines is misguided and even if there were thousands of search engines, why haven't you heard of any of them except the few you know? Any service promising such lies.