Is google and keywords the best way to help rankings?

[kapil_prk]

Definitely Google Ad-word (Keywords is a part of Ad-word Campaign) plays a vital role into online marketing, It helps you to draw customers on your website which leads to gain in terms of Site ranking.
Being Google is the most popular search Engine in current scenario, its not even required to think for other search engines like Yahoo and Bing as you have mentioned. if you will work on Google ad-word correctly and specifically it individually will provide you much success.
Pay per click campaigns are good but the only negative point about it is that in case the keyword you have selected is common than you would be ended by paying big amount for per click. and this much cost to draw a customer only to visit a site somewhere looks like burning hands. By choosing this option your marketing budget will go high.
One more aspect if you are doing these SEO than you have to give enough amount of time to manage it otherwise you have to hire a dedicate resource for this work.
Best of luck for your business.