first shoot with omd... noise reduction advice...

Some of these may be the same answers you got before, but here goes:

1. Is in-camera noise reduction applied to raw files?

No, it's not. Raw is raw.

If you're interested in using the jpegs, yes. I found (shooting with the same equipment as you) that the best settings for detail at high ISO were Noise Filter Off (or at most Low), Sharpness -1.

Depends on the white balance and degree of dynamic contrast. If the lighting is incandescent or heavily red-tinted, probably around 3200, but if the light is just dim but "even" and natural-colored, I'd go as high as 8000 or even more. Blur is almost *always* worse than grain.

You might not want to use auto ISO, but instead turn the ISO up and down as you see fit. This depends on the range of lighting you'll be dealing with. Remember, auto ISO doesn't understand subject motion. I'd use manual ISO, changing it as needed to maintain a good shutter speed, and aperture priority at f/1.8.

I don't really know this, since I was usually in situations where subject motion was a bigger problem than camera shake. I'd think that you could get some good results at 1/20 or 1/25, but I'd also think that subject motion would be a bigger worry than camera shake unless you were quite far away. I'd advise putting the camera in high speed burst mode (make sure you turn on the menu option that enables the IBIS in burst mode!) and fire off bursts; this will really improve the odds that you'll get at least one shot where both camera shake and subject motion aren't a problem, and people's facial expressions (even priests, I guess!) can change rapidly. But be careful with the buffer.

In general, you usually need a faster speed than you think you do, unless your subject is absolutely static.

I found the E-M5 + 45/1.8 a pretty easy setup to get good results from, honestly.