Disregard 90% of what they say in the Apple store
IME the vast majority of information they provide is mostly incomplete, hence them not being aware of other viable solutions. The 'genius bar' moniker is sometimes a misnomer.
In summary regarding your quest to print, it depends on what you want to print from the iPad, and what hardware you implement in your home network. If the iPad doesn't have a internet connection via a cellular network, those items from the internet would have to be downloaded elsewhere, saved on the device, then printed out later at home with the iPad.
Baseline hardware needed:
-Wifi or ethernet enabled printer. (Older ethernet-only printers can easily be connected to wireless routers, fwiw.)
-Wireless router. I will repeat, contrary to what the apple store says, you DO NOT need to have DSL or Cable internet to print from the iPad to a home network.
-Home computer to set up/adjust the wireless network/access the router settings (easier than doing it on the iPad, anyway)