by adding google search box on my ecommerce site can i gain some bucks? is it adviceable?

yeah you can you have to do it through adsense and if people then search through you then you get some money. it works on the same priciple as pay per click. if you want to add a search box you might as well do it that way, doesnt look or work any different

Yes, I have added !

Don't expect a lot, but every little bit helps.