I have a few questions about Fritz 13:

1. How strong is the new Fritz 13 engine compared to Houdini and Stockfish?

2. Is the "Calculation Training" feature that was started in Fritz 11 still available in this version?

3.  What "training modules" are included with the program?

Thank you.

Karl

Also wondering if you can load the 4 million game database into Fritz 13, or does it have a limit on database size?

This is actually my first response to a post ever and I hope it's not too late!

1. Fritz 13 is in the top 5 strongest engines as of now. Houdini 3.0 is the number one. 

2. Yes, calculation feature is still in Fritz 13.

3. A few of them such as defense training which enables you to find all pieces undefended. The same thing for attacking pieces. There is also a bindfold option (which I love). Another feature that springs off of the tip of my head is the endgame training. You can import/input your own puzzles and/or use the default one that comes with Fritz 13. 

I hope this helps!