Most hosting companies do nothing more than provide you with server space and a control panel which allows you to manage your account. Your host would typically not be answering questions regarding how to set up a new theme, installing plugins, or how to upload a PDF and add it to a post. Fortunately, these questions are answered on the internet.
It sounds like you might being looking for a web developer more than a host. If you need more involved help, this is were a web developer can help. Freelance websites like Elance.com or Fiverr.com allow you to ask for some professional help. Many web developers can assist you with finding a good host, but rather than trust them, webhostingtalk.com is a great place to ask around and search for reviews on webhosts.
Be warned, there are plenty of unscrupulous hosts out there that create their own 'review' websites on which they rank themselves as number one. Also, many web host review websites are paid advertisements, basically, who ever pays the most gets the top rank.
Regarding hosts, many Linux hosting servers have everything needed for Wordpress to run, so there normally isn't a need to insist that they specialize in Wordpress.