You are better off paying for hosting because you can not add anything to make money off the site on the free hosted Wordpress. You can on blogger but not on WordPress. With self hosted you can add whatever you like and have full control. You can get hosting quite cheap now days. I pay $1.55 a month for pretty descent hosting. Cool idea for a blog but I would add a bit more content. Like the story of the tea bag.
allout comes to the rescue again! Teabag information would likely be a good thing. Historical information would certainly be a good thing. It can help pull in traffic through SE's for one thing, and it'll give the site more credibility for another.
For image hosting you could use Amazon S3 or Flickr (both cost money for the decent service though). I really like this idea and think it has a lot of potential to go viral... If you need hosting and help with WordPress PM me, I could probably help you out. I'm ordering a new camera today, so should have it Monday-Tuesday, I'll take some pics then