Congratulations, cloth is so much fun! I feel I am still a newbie 8m or so on, but I will try a few quick answers until someone more qualified jumps in to help you out.

1. Normal washing powder, but 1/4 to 1/2 the recommended amount. Some people prefer certain brands without certain ingredients. I'm lazy and just use my regular liquid.

2. Most MCNs are tumble dryable on a low heat but it can shorten the life-span of elastic and PUL. Plus sun drying bleaches stains and kills germs.

3. Most people use something cheaper than AIOs for most of newborn time (flats or prefolds usually) because they need changing so often anyway. I didn't start with a newborn, or know all the brands' packages, so someone else can help you better with that and sizing.

4. Once again, I'm not sure about newborns, but it does sound about right.

5. Every second day is probably the longest you should leave them dirty. I feel pretty safe with about 3 days' worth, but I live in QLD and don't have too much problem with drying time. I didn't take note of where you are, but maybe in a colder/wetter climate you would need more?

I'm sure someone else can give you loads more detail, but maybe that helps a little in the meantime.
Have fun shopping!