did you mean blogs hosted at wordpress.com ? Then NO.. They dont support javascript at all at first point. If you meant blogs hosted by you running on wordpress, you can edit the theme files and put adsense code into it..
Sure, ads are accepted on blogs using wordpress. In fact, there hundreds of thousands of blogs using worpress themes that use adsnese.
ya adsense can be had on wordpress... do some googling out for adsense plugin for wordpress and u r sure to get some real thing what u need.....its there and all do it....
Get a domain and web hosting - they are cheap - about $7 for a domain and $5 web hosting per month. Then use Wordpress and enjoy...