Questions about ad placement in my site

Hey,

I have several websites. I want to ask some questions about ad placement there:

1. In one of my sites I have adsense. It says the site is showing ads but when my friends from different countries checked the site they did not see any ads. Is there any way to verify it?

2. Does anybody knows a good plugin for WordPress and shopify (2 different ones I have sites in both) to make ad placement easier and more intuitive? I think my ad placement is not optimal because I see visitors but not many clicks

3. Related to 2 , I get many visitors but not many clicks. I use google adsense. I know they pick the ads, is there any way to improve click ration? I tried doing experiments in adsense but it did not help

Thanks

look at some of the top sites in your keyword and see what they're doing.