Immigration: deals with people and passports (and visas if you need one, which you don't in this instance) and whether or not a person has the right/permission to enter a particular country

Customs: deals with everything other than people, and is concerned with whether or not appropriate tax has been paid when bringing goods into a country. In some places (the U.S. and New Zealand are good examples) Customs includes controlling the borders for introduction of non-native plants and animals, as well as introduction of pests which might harm native plants and animals or existing agricultural endeavors.

Customs in Munich means choosing the green- or red-colored side of the central exit at baggage claim. Controls are random (or not so random, maybe), but not general.
Usually you walk just through without getting interviewed by a Customs officer.

After leaving thru Customs exit turn left, use walkway to lower level for trains (follow "S" for suburban trains). Not so cheap (€ 8.80 pP), 5 min walking from baggage claim to station.
Or go straight from baggage claim to the nearest exit to street level and take cab (expensive, appr. € 50 to Munich).

I've found that the chances of getting a jetway on arrival on AF long haul flights have greatly increased since the opening of the 2E S3 satellite (gates E51-76) last year.

IAD flights are scheduled to arrive at 2E. Although there's always the possibility of a last minute change to another non-Schengen hall in terminal 2, I'm finding this less common now than before S3 was opened.

You'll need to clear passport control (immigration) on arrival at CDG. MUC flights are scheduled to depart from 2D. At 2D you'll need to clear security (you always need to clear security at CDG even if the transfer is within the same hall).

I'd familiarize yourself with the layout of CDG terminal 2 http://correspondances-aeroports.air....fr/_index.php so you have a general idea of where you're going.

I've made it as quickly as 15 minutes from my arrival gate at S3 to my departure gate at 2F1, but I had access to fast track lanes at both passport control and security and I ran!

Good luck!

Update: We are back from our trip. My daughter & I made our connection at CDG, but our luggage didn't. We received our bags the next morning at our hotel. We had a wonderful time. We're ready to go back!