but in general, yes, it means Performance.
I agree, at this point the i for injected is somewhat a leftover. They have a pretty long history at making cars, and have stuck with it.
I actually haven't kept up with their model for the past 10 years or so. I've had a few BMWs. A 1988 528e sedan (5 series, e = efficient instead of performance), a 1997 318i sedan (3 series, 1.8 liter), and a 1988 M3. -- that one is special.
Yes, they haven't always strictly held to the naming convention, but you know basically what you are getting. If you say a BMW 3-series, you have a general idea what it is. The years for a model are designated by a generation you may hear about... e.g. E30 (3-series from 1982-1994) or E28 (5-series from 1981-1988). It's a pretty good system, and scales much easier than names do. But it can get pretty abstract. I have never heard of the model you mentioned.... but I would guess it is a 2-series (smaller than the 3 series, so likely a coupe - whereas the 3 is either coupe or sedan), not sure about the engine but you covered that... and xdrive I would guess is all-wheel-drive. They used to put an x in the badge for that back in the 80s.