When I open Newsstand on Apple iPod, I don't find any magazines other than the featured ones, is it possible to find more magazines using the Store part of Newsstand?
No - You have to click on Search and a serach queery will bring up all results accross iTunes.
The store page behind newsstand is just a coverpage for the iTunes store. You will find that once you have entereed the store from newsstand you are able to browse and download any iTunes content.
It is easier in this case to use iTunes on the desktop of a computer.
You can browse in alternate ways by tapping on release date and then sorting by name, most popular or release date.
However when you use the iTunes store on an iPad, you have the additional option of filtering results by Category, you can then select Newsstand.