I Desperatly Need Filling In.

[circeus]

It's likely that Devimon was a minion of Myotismon, especially if you take into account that his female counterpart, LadyDevimon was also in his employ.

Incorrect. Ladydevimon was in Piedmon's service. There was never any hint of a connection between Myotismon, Devimon and Etemon, AFAIK.

After a conflict with him, Tai and Koromon end up back in the real world for an hour.

It is not just a conflict: it's the final battle against him, with Greymon first evolving to Metalgreymon!

When they finally return, they reunite the team, with their efforts being thwarted constantly by DemiDevimon, one of Myotismon's henchmen.

And Demidevimon's own efforts covertly countered by Sora in several occasions.

The Dark Masters are a group of four Mega level Digimon, the lower three taking control of an aspect of the DigiWorld each. MegaSeadramon ruled the ocean; Puppetmon, the forests; and Machinedramon, the cities. Piedmon was the strongest of all, and as such, was the de facto leader.

Actually, they reformatted the entire Digital World into Spiral Mountain, with consisted of three spiralling (Duh!) zones of the mentionned type.