Former lighting designer. Simplest solution:
Fridge side - bring your power from the fridge outlet, tuck wire either in the cabinet or right against back wall.
Stove side - the specs say the fixtures are linkable so link from the one you already installed up through the microwave cabinet (or, more visible, tucked under the microwave at the back) and back down. Avoids need to occupy another plug.
Track - hard to tell in picture, what kind of bulb are those? I'm guessing GU-10 in which case you've already got the widest possible beam angle but if there's something else in those, you might be able to get a wider beam.
Once the undercabs are installed, though, consider replacing the center light with a flush or semi-flush light. Now that the undercabs provide task lighting on the counters , you're much better off having a light fixture to provide bright, general lighting - will kill a lot of those shadows.
I'd keep the track over the sink. Task lighting is useful there.