To answer question 1 and 2:
- TBS will be airing the premiere on 5th October at 2:25am (2:01am for 2nd ep, and subsequent eps will be at 1:55am).
- Broadcast on MBS will begin on the 14th of October at 1:55am.
- Broadcast on CBC will begin on the 18th of October at 3:20am (2nd and subsequent eps at 2:50am).
- Broadcast on BS-i will begin on the 26th of October at 1am.
3. Currently the number of episodes is unknown.
4. According to (the sketchy)
AndrewLB Fansub Wiki, the following groups have shown an intent to sub Clannad:
- a.f.k., Eclipse, Fallingsnow, Sprocket Hole Subs, idPRO