Switching to a wordpress plugin

I bought my domain name through dreamhost, and moved the hosting to wordpress.com just because I didn’t know a thing! Now I kinda do and would like to switch back to using dreamhost to host, and install a wordpress plugin. Does this mean that I will then be able to have advertising on my blog (eventually)?
Will my premium upgrade that I paid for with wordpress.com also be transferred to this plugin?
And does anyone have any tips or good step by step instructions they used to make the switch?

You can have advertising on your sites hosted here, but your paid upgrades will not transfer over. If the analogy helps, paying Starbucks for a Gold Card doesn’t get you and perks at another coffee shop.

WordPress has directions on how to move from .COM: http://en.support.wordpress.com/moving-a-blog/#moving-to-wordpress-org

If you have problems with it, I do recommend hiring them for the guided transfer. It works.