What happens when you remove the MIDI device and just have Kontakt Player?
Have you tried loading one of the TriggerTest files to test your environment?
2) 32 vs 64 bit: C:\Programs Files points to 64 bit applications and C:\Program Files (x86) points to 32 bit applications. Assuming you're wanting to run Sibelius in 64 bit, you can ignore the x86 directory. So, place just the Kontakt 5.dll file (make sure it's 64 bit) into C:\Program Files\Avid\VSTPlugins. (I highly recommend you do not place either of the two DLL files that has "out" at the end of their names - they're unnecessary and just clutter the Configuration dialog.)
I recommend you remove the two files that contain "out" from the Avid VSTPlugins folder. Then rebuild the Configuration.