Do we get the source files?

They might be able to obtain it, as some forum members have contacts with insiders at Ubi, but whether they will share this information with the community is something I highly doubt!

Regarding alternative methods, you need to look for specialists on forums specializing in reverse engineering!

What's the point of obtaining them if they don't know how to use them, or to share them with the community (which would be logical, even if not for free, but anonymously)? Otherwise, what's the use?
Reverse engineering is the last resort, but it seems to be the only option in the case of Heroes. Even if a group of such specialists is assembled, it is unknown how much time it will take to create a version with functionality equal to the alpha version (if I understand correctly, reverse engineering implies writing the game code from scratch).