I don't think you need any plugins/software to insert keyword. You can do it easily as you write others. you can put your keyword into the anchor tag.
Regularly update your site.......... share contents to the social networking site......... do some off page SEO and on page SEO
Best way is update your site regularly. Choose right keywords for your site. Share your site to the social networking site.
SEO keyword is something by which any search engine can show the related results.
May be there is another issue. I haven't heard that google has blocked any account due to inactivity.
Edit your Blog theme/template . This can be done by your website/blog.
Most of the time Google doesn't shows the reason why they block the AdSense account.
It actually depends on the Keyword and traffic. So try to increase the traffic from US,UK, Canada etc.
It doesn't low at all. Its quite impressive.
Yes, age does matter. For some specific countries Domain age should be 6 Months.
Check your Adsense account regularly. Check there if any unusual activities. Use some tracking tools to find out the IP address. If you get the...
Google adwords keyword tools is the best tool on which you can depend on very much.
I use Google Adwords keyword tools and I think it is the best tool as far i know.
As per I know AdWords Keyword Tool uses Google Search Engine's data to analyze keywords. Semrush also uses same but don't know how much accurate.
Separate names with a comma.