Well, on the subject of bots, I'm sure that the community is already working on it. Good thing about the D3 engine is that it should be quite easy to open each map in Radiant and generate an AAS file as opposed to Q3 where you don't have the map files to work with.
OakBot is being done specifically for Quake 4 but there might be others in the form of 'ports' of D3 stuff, 'TinMan Squad' is one I can think of (co-op for SP but TinMan was working on a 'bot' for D3 MP iirc).
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