The problem with the 40D that pplneedthelord has is exactly what it is- a one to two second delay at times when the camera is in non-timer modes. I borrowed his camera for my concert shoot and it happened about 10 times in the two to three hours of shooting. It's abnormal, so do send it in to CSC for a check.
As for the funeral / wake, try not to use flash (bump to ISO3200 if necessary, it's unlikely that the family will be printing so big that noise will be a key issue), and also be sensitive. Don't do a 6-shot burst when it's very quiet, for example. You can try using your 40D's silent shutter with the Liveview.
As for the procession of the coffin to the casket van, always always stay ahead of it in a discreet way, but not directly in front so much so that you block the passage.
Hope your shoots go well.
Cheers,
Zexun