Lighting, Light Fixtures, Ceiling and Exhaust Fans - Add 2 under cabenit lights to existing over sink light

Can someone verify my plan?

I have an existing single switch and single plug combination receptacle. There are either two sets of wires coming in or it's just one coming in and then going out. In any case there are 2 white wires connected together and then to the switch/plug combo, two back wires connected directly to either side of the switch/plug combo and two copper wires are connected to each other. The switch powers two lights and I want to add two more Xeon under cabinet lights to the string. The existing lights are wired in parallel and the cable is stapled along the top of the cabinets so since I can access it easily my plan was to simply run cable between the cabinets (there is a 1/2 inch space to run cable down and back up) and add the 2 additional lights to the existing sting.

If necessary I can lose the plug in the current receptacle and either try to find a single receptacle box with two switches rather then the two plugs or lose the plug and move to just one switch - which ever is better.

Also, Should I use different lighting then the Xeon? And do I need to loose the existing halogen lights and use 4 of the same type?

Shamelessly bumping this to the top. I have always had good luck getting suggestions and information on this forum so I'm a little surprised there has been no response yet. If my question is confusing please ask me questions and I will try to clarify.

I have found some information by doing a search but nothing that pertains exactly to my situation.

Connect the new lights to the existing lights at the existing lights. Do not change any connections at the switch.