electricallight-fixturelightingrecessed-lighting
I have a can light (recessed light) that I need to convert to hanging a pendant light. The conversion kits have you plug into the socket, and I am hanging a dimmable LED fixture with a wall dimmer instead of a switch.
Is there any issue with it being dimmable since you're not directly wiring it to the switch? i.e. wiring to the socket adapter -> screwing into the original can light socket.
Here is the socket: 
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.
Since the same switch will control the light over the sink (which you are swapping to a recessed light) and the lights over the island, this is easy.
When you add the wire for the island lights, use the junction box on the new recessed light can for the make up. This is no different then connecting multiple recessed light cans together.
Best Answer
I recently did the exact same thing you're evaluating. We used a conversion kit to install a pendant light above our sink where there was previously a recessed light. As far as dimmability goes, that's mostly up to the switch and the bulb you have, i.e. you have to have a dimmer switch and a compatible, dimmable bulb. We went with Leviton in this particular instance, though we have Lutron dimmer switches elsewhere.
One thing we've noticed, since we're dimming a single bulb, is that we have to find a "sweet spot" on the dimmer to prevent flickering in between brightness levels. It's a minor nuisance for the flexibility of adjusting the brightness.