The workflow I envision is to do my image processing and story development on my desktop or laptop system, generate the output in the appropriate form for the iPad, and then move it there for display, distribute it to the web for others to download and enjoy.
That's how it integrates with my personal and professional photographic world.
The cellular data service is a no-contract, month-to-month term service. Enable it and pay for it when you need it, cancel it when you don't. You're not locked into a $30 a month payment unless you want to be. I think it's probably worth the extra $130 to buy it if you think you might ever need it, but you don't even have to turn it on, ever, if you don't want to.