Everything Mario said...

I work in Logic. Put the midi tracks in and then use my own instruments. Be aware that when you move the midi files into your daw there is 'hidden' info in the midi that makes using some instruments tricky. For instance, there is some info in the midi that makes it impossible for me to use my Korg Triton plug-in. The midi info overides whatever instrument I select and switches it back to whatever instrument the midi wanst... Sometimes you can get around this by opening the daw midi editor, selecting all the notes and then copy and paste all the notes into a new track.

Before dragging midi files into your daw, open the BIAB mixer window and set all panning to zero and all volume levels the same. This will make it easier to mix in your daw.

Once you have the midi in your daw you can edit notes, cut and paste, move parts about etc.

Chris
More of my music at: https://soundcloud.com/user-663569023