I just opened up my first photo account with flickr and it was amazingly easy to upload several hundred photos from a trip to the botanical gardens and then email the series to friends. It's so simple even my grandmother can use it.

I'd advise you to work on your copywriting. With all the free photo hosting sites out there already I don't think people care about average number of photos times x number of cents to host per year. They just want to know how easy it is and that it's free or that they are getting an incredible deal by paying a subscription fee.

If you're targeting people who are new to the web, talking about zip archives will likely scare them away. Keep it simple.