Wow, you have collected a lot of Speeder's tidbits already! I'm impressed (I must admit I miss a lot of them)
We are in the MO IRC channel, yes. And yes, anyone can join.
MO staff are most active during the afternoon and evenings of European timezones. For me living in Singapore (GMT+8), it means 12midnight to 7am. You can imagine my lifestyle. 
You can use this to determine when we are most active.
We do not talk about development all the time. We talk dev when we have something to show to our peers. 95% of development happens 'privately' - meaning that most work is done outside the internet.
This is probably what happens on IRC in 24 hours (values are a rough estimate):
40% - Silence, and mostly people from China roam the IRC. Developers are sleeping.
20% - Developers are around, but are silent as there is nothing to say.
20% - Some people (including developers) post random stuff.
4% - We argue for beta, and Speeder waves hand.
4% - We 'party' (or make a general fool of ourselves).
4% - We discuss other games.
1% - Speeder posts some screenshots of some 4th side units.
1% - I post some screenshots of a mission, or write several lines for discussion, which probably only Speeder and some others can decipher.
1% - Omegabolt posts some work on Red Ressurection.
1% - Mevitar wearing several sad faces.
1% - Someone discusses crashes, and AlexB or some other person determines their root cause.
1% - Someone discusses ini rules.
1% - Some Ares feature discussions (e.g. paraphrased - mevitar: you used Gattling Cycle logic for the charging effect? Speeder: yes.)
1% - Complaints surrounding the multiplayer lobby reaches IRC.
We do talk and 4th side is one of the topics. Maybe you came at a wrong time. Stay with us for a longer time, and you can find out more stuff.
There may be more events in there.
