Train from FRA
 

I am planning to take a train immediately upon arrival at Frankfurt to Munich. There is a sizeable amount of savings if I book now verses at the airport, but if flight cancellations are common I don't want to be holding the bag as these are nonrefundable. How much time should I leave between the scheduled arrival time and the train (traveling on SN and don't see a clear rail and fly option)?

Deutsche Bahn has an extraordinary sale this weekend, 20 Euro-tickets anywhere! Of course they are not refundable, but compared to the 91 euros normal fare, I would not mind risking it... add at least an hour between arrival of the plane and the train, maybe two... there is enough to do at the Airport.

Yup this is exactly the fare I'm talking about. Maybe I'll just pick the train 3 hours after my arrival and cross my fingers. Any suggestions of things to do at the airport? Assuming on time arrival, could I make it into the city or that would be cutting it close?

It takes roughly 15-20 mins to make it into the city. When you're choosing your train, look at its route. See what trains go between Frankfurt Hbf and Munich Hbf and just board the train at Hbf instead of at Frankfurt Airport.

Good suggestion. Is that permitted? They don't do controls between the airport and the city?

they love to control tickets between airport and city center and write lots of 40 euro fines out to foreign tourists. If you manage to get a 20 eur ticket for a connection that involves a regional train or S-Bahn between airport and Frankfurt Hauptbahnhof, it would be the best, as you are flexible on that segment and can take the S-Bahn or RE that goes every 10 minutes or so. if you get a 20 euro ticket only from Frankfurt hauptbahnhof to Munich or with ic/ice from the airport via city center, just buy a single ride for the s-bahn for 3,xx euros to get there, if you have time and are early. Unless you are looking for drugs or sex, dont just get off at Hauptbahnhof but continue to Haupwache or Konstablerwache.

Good advice. Any thoughts of whether Haupwache or Konstablerwache would be better given a compressed timeframe?

Definitely Hauptwache.

Fotr sightseeing, it is just a short walk (5 minutes) down to Paulskirche, the rebuilt old city center around the roemer place and the emperor dome. Directly around Hauptwache there are also lots of cafes and shopping opportunities with the MyZeil shopping center just a 2-minute walk away.