Lighting – How to dim LED recessed lights that are on the same switch as two ceiling fans without slowing the fans down

Conversion is too soft a word for what will have to be done, it is more than likely going to be a rework.

Somethings you need to figure out:

I would like to add a ceiling fan/light to one of the receptacles

A ceiling fan is far heavier than a recessed can light and thus needs additional support. The recessed light box will need to be replaced with a special box that braces itself into a ceiling joist or into a wooden block between two ceiling joists. Looking at how the recessed light box is being fastened into the ceiling will tell you how to do this.

and convert the other to a track light with its own light switch control.

This can be done but even in the best case scenario, you will need to run an additional cable from the switch gang box to one of the luminaires. This is of course assuming that the cable coming from the breaker is coming into the switch box.

It becomes more complicated if the power to the breaker is coming into one of the two lights. In this instance you would need to run a 3 wire and ground cable from the switch box to the light with the power line coming in:

NOTE: All of this of course is assuming that if one of these happens to be a fan/light combo, then the fan and light will be wired to turn on with a single switch, rather than separate switches for each function.

NOTE 2: This also assumes that you have already have a double gang box for installing two switches. If you do not have one then you will need to open up the wall and install one.

NOTE 3: The following diagrams assume equipment grounds are properly wired throughout.

The only product that I know of that will do what you want is the Lutron Maestro Light/Fan control. This product consists of a switch and canopy module. The switch will digitally talk to the canopy module over the single ungrounded wire and control lights/fan separately. The kits are one switch and one module but the switch can talk to 4 modules at once.