This should be possible, as it is possible to conenct a printer to a mac with both USB and WiFi at the same time.
Be sure to obtain a printer that supports Airprint, and not just WifI printing. You can find a list of them located here.
the list of airprint enabled printers that GarlandM has supplied is really useful and it's wise to do your research before buying!!
the other option, especially if you are not as technical (I am the same!) is to try a good printing app on the iPad, there are quite a few but you may find something like print n share fairly useful, plus they have good tech support