Yes Denti, that is correct, the 2 WAAS sats are CONUS only for WAAS RNP 0.3, and WAAS LPV, but you get some limited coverage down into S America., I dont know of any plans to float others.
As far as protected areas, not sure where that is going, since GBAS isnt a beam, there is not interferance either from structures or other aircraft like the ILS. You can also have simultaneous arrival and departures, as there is no beam to block...
Currently, HoneyWell SmartPath is only certified CAT I, but are working on the other certs. Right now, as far as I know, Smartpath is the only GBAS system that is certified. The Russians had one, but rushed development before the ICAO specs were done, so the system they have will not work with the others...
I know a few military entities that GBAS to CAT III autoland, and yes it does work perfectly.
Now, both Airbus and Boeing offer the GBAS "option' for free with all current models when ordered new, you just have to ask.
Unfortunately, due to the budget fiasco with the FAA in the last few years, the FAA has given up on GBAS, as redundant to WAAS. This is most unfortunate, as the capabilities are completely different.
While the WAAS augments the GPS signal, and provides a fine tuning...GBAS augments GPS, but also adds the final approach procedure, even to include a turn to final.
I was able to provide multiple GPA's, displaced thresholds, final approach with a turn, or the best scenario was RNP transitions to a GBAS final...perfectly seamless.
The FAA was stung by using Newark as a test, because the freeway next to the runway was full of trucks with GPS jammers, so they were constantly losing the signal.
There was another installed at Memphis, but the FAA let that one die, and go non-op. Looks like it is being resurrected at Houston to further Continental (United) use of the system to pair their Newark/Houson flight op..
Boeing has one installed at Moses Lake for validation purposes.
You mentioned Bremen, and Malaga, and there is also Sydney still operational.
Given the system capabilites, I really find it difficult to understand why it is not more widespread. It doesnt help that the FAA is out of money, or that while the SmartPath is Honeywell, you have to use a Rockwell Collins MMR on the aircraft...now who didnt figure that one out?
