Hydraulic Disc Brake (how to choose correct model)
As Argenti said in comments - mixing levers and calipers is not recommended.  

Magura's website is very informative on what Magura parts go with what Magura brakes and how to select parts. I did not find any Magura / Shimano cross reference.

There is a very nice explanation of the pros and cons for different hydraulic brake configurations to aid in decision making. Here is a chart describing 2 vs 4 pistions:

Two Piston vs 4 Piston vs Trail Combination (4 Piston Front / 2 Piston rear)


The page also has information on Magura specific rotors and brake pad performance and an interactive guide for setting up brakes.

Magura also makes a one finger aluminum MT4 compatible lever.