where can i find the duties, tariffs and taxes of countries if I am sending product from USA?

When you are trying to export items to abroad, as an exporter, you can refer to the following site, provided by the US government. It provides a lot of basic but useful information necessary for traders.

http://export.gov/logistics/eg_main_018130.asp

And also, if your export destination are some Asian countries, such as China, Taiwan, Japan and South Korea, you may refer to http://www.itsilkroad.com./ The site provides real-time trade cost simulation service in relation to your trading items, including duties, internal taxes, tariffs, ocean or air freight, and export/import requirements by country.