Yes, your order of events is quite right there, Sloth. As for the divided Macedonia, wouldn't it be better if the player controls Antigonos Gonatas, like on RTR VII, instead of Ptolemy Keraunos? Since he died very shortly after and having a Pseudo- Ptolemaic or Sosthenian dynasty in Macedon instead of the Antigonid dynasty would be a tad strange
I'm not sure how we are going to put this all in game. The problem with hordes is, that this only works when the Galatians don't have any settlements, but right now the Gaul faction also represents the Gallic tribes in Gaul itself, the Celtiberians, the Helvetians and other tribes in Switzerland, the Norici, Boii and Skordisci and probably others I forgot. In 278 BC, King Nicomedes of Bithynia invited 10 000 Gallic warriors into Asia, so they would help him in a civil war. He wins, but then another pretender (Zielis or something) hires the Gauls. Even though he is defeated, the Gauls plunder around, then offer their services to Pontos, make trouble again, are dismissed and settle in Inner Asia to ransack everything around them and give the region it's name Galatia. So basically we have three stories here:
1. The Gallic invasion of Greece and Macedonia, which ends in defeats on the hands of the Aitolian League (Battle of Delphi) and Antigonos Gonatas' Macedonians (Battle of Lysimachei).
2. Following on from the defeat in Greece, the invasion of Thracia and the destruction of the Odrysian Kingdom of Thrace. This obviously leads to the foundation of the Kingdom of Tylis.
3. The Crossing of the Sea into Asia, with Gallic warriors in Bithynian services, before they settle in Galatia (not only 10 000 warriors by then, but four or three ''nations'' (big tribes, like the Aedui or Helvetii, numerically/organisational speaking).
That leaves us with 100 000 - 200 000 Gauls in Thrace and probably an even higher number in Asia, both of them steadily increasing.