All of your questions are easily answered and pose no real problems. They said that Old World Blues will help explain some mutated monsters of the wastes. So, I'm guessing FEV is going to be involved. This is the problem I have with the canon concept. Too many people get hung up on canon. Yes, it helps continuity in the series, but it does not explain what is happening everywhere. We do not know the full extent of the enclave/gov't experiments nor do we know all of the vault system's experiments. And there are many areas of the country we have really no idea what is going on. I bet before fo3 you would have said that FEV ONLY existed in two places. Well, guess what, it was on the east coast too.
And from what i read about the Big Empty, it might have the most scientific resources we have seen yet. I don't know for sure of course, but we will find out soon. And so what if wanamingos failed in the earlier experiment. That doesn't mean they might have a slightly different experiment somewhere else associated with wanamingos. One that experienced a bit more success. Very possible. The point is, don't get hung up on canon. All the canon really does is explain what happened in THOSE locations at THOSE times. The devs could easily bring wanamingos back in my opinion. I don't think they will, but like i said in my original post, I am hoping.
The wannamingos are a result of FEV virus experiments, but they are now becoming sterile. They are not aliens, but word is they were designed as FEV-tailored weapons for waging war on other countries... and they got loose. They do live a long time, but they were dying out at the time of Fallout 2. They have only been sighted in the F2 area and nowhere else in the wastelands.
The eggs you see in Fallout 2 are the last generation of Wannamingoes to exist in the wasteland; the young Wannamingoes seen in F2 will perish in five years, and their parents a few years before that - an internal genetic clock will simply stop ticking, and they'll fall over dead. The Wannamingoes are a vicious mutant breed that had their moment in the sun, and now their sun has set.
To put the tombstone on their extinction, the largest known nest of Wannamingoes were wiped out when the Great Wannamingo mine was reclaimed by Redding with the help of a traveling tribal. The mother was killed, and the last remaining eggs were hunted down, stepped on, and then the remains were examined by local scientists and doctors who came to the extinction conclusions mentioned above.
Again, Wannamingoes are not aliens – they are a curious mutant or genetically-designed fighting machine that has only been able to find a home in the cold, dark places of the wastes.
It is possible that the wannamingoes were old Enclave experiments (or even experiments from before the Great War), and if this is true, then it's likely their genetic/biological deadman's switch was purposely engineered to keep them from breeding past a certain generation.
As a final note, this is strictly a personal decision on my part. If you want them to live for fan fiction, pen-and-paper role-playing campaign purposes, or for your own peace of mind, feel free to have some of them survive the stopping of their genetic clock – in the Black Isle universe, however, the little buggers are already dead and their irradiated shells are scattered along the floor of abandoned mines throughout northern California where they make nice crunching noises when you step on them.
I see no reason why Chris Avellone, the project director/lead designer/or whatever of Old World Blues and writer of the Fallout Bible would go back on his own word.
Sure OWB holds potential for a lot of stuff but what reason is there to add in wannamingo's?
If Big Empty is where they were created then I'd like some data on them from holotapes and terminal entries but I see no point to add in wannamingo's just for the sake of adding in wannamingo's.
Detailed data on how they were created, for what purpose and what the results were is more than enough.
But there's no reason to have them rise from the grave.