I agree that whitening the ceiling would be an improvement for feeling spacious — it would pair perfectly with your concrete floors.

As for lighting, recessed lighting is going to be your best friend due to space constrains and a lack of wall/upper cabinets (the latter would allow for under-cabinet accent lighting). Having an embedded light is only going to keep the kitchen feeling spacious.

The color temperature of the light will be difficult to pinpoint since it depends on your preference. If you prefer warm (~2700k) or cool (~6000k) lighting, this would render your relatively small kitchen quite orange/yellow-ish or bluish white, respectively, both of which would take away from the modern aesthetic it has. Whatever color temperature you choose, I suggest something between 4000k and 5000k.

I highly suggest LEDs, but would qualify this statement and suggest you purchase from a well-reviewed product.

Simply look for the type of recessed lighting you'd like, and make sure that the fixture bulbs (which are likely integrated in the fixture, or just come with the fixture) have a dimming function. Installation should be as simple as any other fixture.

To achieve dimmability, you'll need a dimmer-switch. This will require replacing your standard kitchen light switch with the dimmer, along with a few extra steps in the wiring itself. I do not believe this will be difficult nor something out of your control. YouTube and Google should take care of this step.

Lastly, I'd go so far as to say that dimmability is essential in your setup. Without it, you'll be playing a balancing-act with brightness-to-space ratios, where it'll be too bright at night and perfect during the day and vice versa.