If you want to use a keyboard, the tablet must have Bluetooth and then pick up a Bluetooth keyboard. I think the MS surface pro tabs are the only ones you can plug a USB keyboard into, as they have the port and its a full version of windows. I have a surface 2, which has the port but I have not tried a USB keyboard as the surface tabs have a pretty slick proprietary one that clips on.
I worked in electronic sales for the last four months, Nexus 7is a very nice piece of kit and very reasonably priced. If you did want to spend a bit more, I would go for the LG 8.3 inch tablet. Those things are gorgeous. IPad mini is always reliable, but for the same price the LG tab is WAY higher spec.