Cubase 6.0.7 and Sierra problems

Hi there!
I recently got a Mac Mini 2015 with Sierra and decided to use it for music. Until now I was using a Mac Mini 2011 with OS 10.7. I already installed some other software I own like Live 9 and Logic Pro X and everything runs fine. My favorite software to do music is Cubase. I have version 6.0.7 and I could install it using the tool provided by Steinberg.
I have 2 problems:

  1. the position of the mouse pointer is wrong! If I click say on a track, that track won’t be selected, something different will happen as if I clicked somewhere else. If I set my monitor to 2560 x 1440 the problem disappears. If I set it back to its default resolution the problem is back.
  2. I don’t have many plugins, actually only 4-5 and I like the Cubase plugins. So I make a track with say Spector and when I change preset Cubase crashes in a fraction of a second. I never saw such a quick crash! This happens again and again with no exceptions with other Cubase synths too: change preset 4-5 times and crash!
    So as you see I have 2 different problems: for the first one I found a workaround keeping my screen resolution at 2560 x 1440 and that’s OK with me. For the second one I have no idea and I am quite sad because it makes for me impossible to use Cubase.
    I would really appreciate if someone could come up with a solution or with a suggestion. Many thanks in advance!