4' fixtures will be rather spotty if you are using them for geeral light. The bulb is rather limited. If you must use 4' 12V would be better. Much more choice of bulbs. Any good name brand will perform and gimbal are a nicecoice because they are adjustable. Yo can also use an adjustable baffle as well. They are nice because the bulb is away from the ceiling line so no glare. Don't buy generic 12 volt fixtures. Stick with the big guys on this one. Juno, Halo, Lightolier are all good brands.

Before anyone can give you advise about the recessed you should use and placement, they would need more information than you have provided. Ceiling height, colors of materials being used in the room, cabinet and work center arrangements, etc. Remember all that wonderful light coming in from outside is not there at night! Post additional information.

Here is a link that might be useful: Your Light Site

I have a L-shape kitchen with 3 recessed lights on each side. 8" ceiling, cherry cabinetry with medium stain. I'm also adding a track light over a peninsula and under cabinet lighting.