Well, that depends on a few things. Moving could be as simple as downloading the entirety of your site and reuploading it somewhere else. Or it could be going through each page and correcting broken images and links. So it could be really simple, or it could be a lot of work.
I've never used wordpress.com so I don't know if they have an option to bulk-download your site or if you'd have to do it manually.
One thing I'd say is you typically don't want to buy a domain name through your host (in this case, WordPress). If you do that, you've now connected the domain to that account, and it may be more difficult to change hosts without losing the domain. I bought my domain from Namecheap
but host with HostGator. There's other options out there too, so a bit of research can point you in the right direction. You should be able to find a tutorial online on how to connect your domain to your site (your host's website is a good place to start looking).
Since you don't have your own domain name, you'll have to direct your readers to the new site. If they're interested in your comic, this shouldn't be a problem. People that are just relying on feeds may miss the update though. But I don't think that would be a big issue if your last update on the site was an image saying "Hey! We're moving! Go here now instead!" that clicks through to the new site.
Whether you're willing to buy hosting or if you're looking for a free home will affect what you're looking for. If you rent from a host, you should be able to install the WordPress software on it (if you want to continue to use it). If you're going the cheaper route, there are a lot of options: ComicFury
, Comic Genesis
, etc. I think there might already be a thread here about different comic hosts, but I can't remember.
Before you buy a domain name for one of the free hosts, you should check if they allow you to set up your own domain. But having a set domain would help clear problems later on if you decide to switch hosts again, since you could make a move and your readers may not notice much more than a bit of downtime.
Since your site isn't very old, it would be better to make these changes now than wait.