Safari on my iPad does not have tabbed browsing so I use an Atomic Browser app. Will I face the same issue with Lion on the new MBA?
No - Safari has tabbed browsing in OS X - or you can use your preferred browser, whatever that might be as long as it's not IE.
Maybe it is just me, but I found FF (5.0.1) to not support some of the new features in Lion including basic gestures such as the two finger sideways swipe for forward and backward.