What is the official way to:
 
Import a track from another project into current project
 
Export a midi clip as a midi files to a folder
 
Export a midi track as a midi file to a folder
 
Export multiple midi tracks as a one multitrack midi file to a folder
 
Export multiple midi tracks as a multiple midi files to a folder in one move
 
Import a midi file and put it on a track, drag and drop style
 
I experiment with this and I am confused
 
 

bump... sorry

MIDI has two modes. In Mode 0, it will create one file. This will be default to channel 1 unless there is extra channel information like midi assignments and bank changes, pitch bend etc. exported in the MIDI file. In which case it will be Omni meaning channels 1-16 are incorporated.
 
MIDI Mode 1 separates the files into individual tracks and System Exclusive information can be carried across.
 
You can drag in a MIDI file,create a MIDI track, open a MIDI track or Import one from the file menu.
 
Anything else is Mastercard.
 

Drag 'n drop?

Yeah sure. If you have Browser open at the side panel. You can drag in a MIDI file part from there. 
 
If you want to retain tempo changes etc. You are better to just open the MIDI file like a project as it doesn't seem read the tempo map any other way I know of.
 
Maybe I'm not understanding the question....
 
 

I use the browser for all my midi import and export.
For importing: Simply grab the file and drag it in. Exporting is a little different.
you want to make sure you select the portion of the clip you want to export (by splitting) then use the bounce to clips function. if you don't you will be exporting hidden data/slip edit data.
Once you have the clip or midi track ready, just grab it by the top portion of the clip and drag it in to the browser.
 
NOTE- make sure to create a folder in windows explorer first as Sonar does not have the ability to create folders within the browser. Once you get the jest of it, it is just as easy as it appears. Its simple.
 
This is for basic midi tracks (Type 0 is a single track of data) within sonar.
Not Karaoke midi tracks (Type 1 files contain separate information for each track)