I think if you have the lights above the mirrors, that centered above them and should be smaller than the mirrors. Pointing up or down seems to be no wrong or right, simply a matter of personal preference. I think sometimes it depends on the light itself, some look better pointing up aand some look better pointing down. ( I have in my master bath two 3 light vanity lights pointing up above my mirrors, In my hall bath, I have a 3 light one pointing down. I like them both.I guess I was no help other than to say the light should be less wide than the mirrors.

"We are taking down an extra large square fluorescent light and replacing it with one two-bulb type flush mounted light and maybe another if need be then also adding a pendant over the sink." It will depend on the size and layout of the kitchen. One flush mount will not work as good as the fluorescent for two reasons. (1) The fluorescent puts out 6.5 times as much light. A 4' fluorescent with 4 tubes (2600 Lumens × 4 = 10400 Lumens) A two bulb flush mount w/60 watt bulbs or equivalent (800 Lumens × 2 = 1600 Lumens) (2) The surface mount fixture's light source comes from exactly 2 points that are very close together. The fluorescent light source has infinite sources of light within that 2' × 4' area which spreads the light out better, causing less noticeable shadows. With the fluorescent, the light reflecting off of all the other surfaces in the kitchen is also bouncing off at a more infinite number of angles, (compared to just from the pinpoint light source of the standard fixture) further contributing to the feeling of even light in the kitchen. . Pendant lighting that is bright enough to really contribute to the overall lighting of a room will also be glaring, since it is down closer to eye level. Pendants are fine for specific task lighting or mood lighting. Under cabinet lighting can also be a bit glaring if it is relied upon for more than half the light needed for a task. Keeping the under cabinet lighting out close to the face of the cabinet helps. Using two surface mounted luminaries on the ceiling will help spread out the light sources and help the light bouncing off of the cabinets light the room more evenly. Whether I would use fixtures with two or three bulbs depends on how big the kitchen is, how much light you are used to, and how intricate your tasks are. 800 Lumens × 6 bulbs is still only 4800 lumens, or less than half of what you currently have. You could try taking out two of the tubes and living with it for a while to help decide how many fixtures you want on the ceiling. . The difference between two 3-bulb fixtures and recessed cans over the outside edge of the countertop should not be enough to worry about as long as you have the under cabinet lighting and the pendants. There is a trade off between the two types of lighting. The recessed lights can be put right where you need them, but the light does not spread out as evenly. The surface mount in the middle of the room can produce more unwanted shadows, but the light spreads out and bounces off everything better to counteract the problem.

I recommend LED wall packs and LED flood lights, which are very energy efficient and make the outdoors very bright and full of fun. I used it two years ago. These two types of lighting effects are good for outdoor lighting.

IKEA https://www.ikea.com/us/en/p/arstid-led-picture-light-nickel-plated-10355627/ https://www.ikea.com/us/en/p/brynet-led-picture-light-black-90389223/ https://www.ikea.com/us/en/p/brynet-led-picture-light-silver-color-70389224/ https://www.ikea.com/us/en/p/maglehult-led-cabinet-picture-light-black-30464890/ You can also use swing arm library lights to illuminate the art.