The latest SW version for X2-01 is 8.71 on India, and 8.70 for most of the other regions/countries.
7.22 does not seem a valid SW version for Nokia X2-01 though. Can you type *#0000# and see what the model number field says? (just to be sure that we are talking about the correct device model)
The device model I am talking about is the Nokia X2 that has the qwerty keyboard. That is the Nokia X2-01, right?
I am in the USA, does that mean my Nokia X2-01 should be on software version 8.70?
Ok, so it would appear that this is the US operator variant of the device (T-Mobile, RM-717) and not the global variant. There were no further SW versions released after 7.22 for that device variant unfortunately :/
Not sure about the First part of your query..but to answer the other.. Updates provide Bug fixes, New features, Performance enhancement, etc. to name a few ...
I have to say that unfortunately there won't most likely be any further updates (the last SW updates for the device were from 2011).
farby already mentioned the typical contents of a SW update, but those vary case by case.