Cree's recommendation to me for dimmers with the 10 LR6's I will have on one switch (and the 3 on a 2nd switch and 2 on a 3rd switch) are the Lutron Skylark SF-10P (single pole) and Lutron Skylark SF-103P (3-way). Not as cosmetically sleek as some of Lutron's other dimmers, but I just want 'em to work w/o issues.

You can get IC rated shallow cans from Halo in both new construction and remodel design. See the link below. With the nonIC cans, you need to leave space on all sides. But why do you want to poke holes in the ceiling and in the insulation to install a heat producing fixture that will pull conditioned air from the room? Here is a link that might be useful: Shallow cans

I'm not a mother (but I am an aunt to 6 kids) so I guess take my ideas with a grain of salt. I'd go with some sort of adult lighting which complements the space (perhaps one hanging fixture, or a row of them on the beam?) And, add in some table lamps to make it cozy. I would think the main goal would be to make it nice and cozy for a small child. My view is that the decor should be functional and should not have to be changed out as the child grows. You can bring in the "fun" stuff with linens and other accessories, rather than getting a bunch of stuff a fickle child might not even like down the line (or appreciate at age 2 1/2) and which you'll just end up getting rid of. Then again, I have never really understood decorating children's rooms or nurseries in strongly "child-like" or baby colors and themes. ;-)

We recently put all new LED ceiling lights in as part of a larger whole house remodel. Although not in a bathroom, for the slanted ceilings in kitchen and family room, the GC wanted to put lights that pivot (I think they are called Gimbals). We rejected that and had them install normal LEDs that do not move. The ceiling lights create general lighting, and we didn't feel we wanted more directional lighting coming from the ceiling. In a bathroom your task lighting will be sconces in or on either sides of the morror, or lighting over the sinks. This is a personal choice and the GC was surprised we didn't want the gimbals, but we really did not. Other things to consider are the temperature of the lights. The higher the number, the more cool/daylight the light will be. I prefer the more daylight ones. Also, it's nice to put them on a dimmer so you can control the brightness. I can't recommend a particular brand because the electricians buy them in huge quantities and we went with what they supplied.