I think that I know this answer already but will ask

MUC-FRA ticket in Economy

FRA-Canada ticket in Business

I have 1.5 hour connection in FRA and want to check luggage straight through (should not be a problem; last week I did this DEL-FRA-CDG on two seperate tickets, with DEL-FRA as business, FRA-CDG as economy)

For the MUC-FRA, will economy or business rules apply? will domestic or long haul rules apply?

I am guessing domestic economy, but if business long haul that is a big difference! I am stocking up on 3 months supply of chocolate and coffee so luggage will be near the business class limit