(1) These German colonies are what plunged Europe into war?
(2) Regarding empires, UK, which had the most to gain, was much more ambivalent about fighting Germany than France/Russia were. At it's heart, it was a conflict about Europe.
(3) It's argued that in 1914 the outlook for peace was stronger than in the preceding years because two Balkan wars had come and gone without expanding into larger conflict.
(4) Another lecture. Around 45:00+ he makes an interesting distinction that seems to be playing out in this thread. If you ask
"Why did WWI start?" the answer is more framed in the bigger picture (alliances, empires, so forth). If you ask "
How did WWI start?" the discussion is a bit different, focusing on events in July 1914. It becomes more about breakdowns, and less about blame.