1) EB includes both a formation mod and aids for the strategic A.I. However, as anubis88 writes, this is not something that can be changed a lot through modding. In the unofficial submod forum you can find Sinuhet's and Darth's formation mods adapted for EB. These further improve battle A.I. but again: don't expect miracles. They merely raise the level from bad to unimpressive.

As for the alternative .exe's: BI.exe does not improve strategic or battle A.I. It does, however, make the A.I. more likely to carry out naval invasions. That can be a downside, as I've seen several pointless naval attacks carried out by too small armies, for no other reason than that the A.I. shared a stretch of water with me. I haven't tried alex.exe yet.

2) We generally don't allow comparisons between different mods, as this would lead to fans of either mods slagging each other. As such, I won't say which one is better, merely state their philosophy. Both EB and RTR try to create a version of RTW that is as realistic as possible. EB goes further in their quest for accuracy, while RTR is more accessible and less resource intensive. Darth mod on the other hand is not much concerned with accuracy: its battle A.I. is reputed to be the best of any mod. His formation files have been adapted for EB, but the full Darth mod is supposed to be even better.

In case someone wants to take this discussion further: no mod-bashing, please.

5) Reload-bug? You mean the save-reload bug that made the A.I. forget which cities it was attacking when a game was reloaded? That was fixed in R:TW patch 1.3. It's not present in EB.

6) No, but check out the FAQ and the EB guides forum.