Despite urban legend and the plumber's union - you do not NEED a fan for the toilet! You do need a fan to exhaust warm moisture laden air produced from a tub and shower out of your house. This moist air is what can wreck havoc on your structure long term. Now, you may want a fan to get rid of methane around the WC, produced by its users - but it is not necessary as the amts of gas produced are not enough to cause harm. Here is a link that might be useful: You may find this fan / light helpful in your design

PS My GC's electrician was here today (he is very experienced, does lots of high end homes around here - which includes MCM). He said he has the Fantech 4" fan grill/light combo and loves it. Prefers it to the Panasonic WhisperRecessed - even though he admits he doesn't have it - because the motor on the Fantech installs away from the ceiling, so no chance of vibration (and thus additional noise). That all said, reviews say the Pansonic is very quiet too (and, well, some white noise in a bathroom can be good!), and I think someone going for your aesthetic should investigate the Panasonic b/c it sounds like (but I'm not sure) the placement and adjustability of the light bulb in it might work better for you - sounds like from their website that it can be recessed far up casting a different area of light. Something like that. HTH!

A kid's bathroom usually means a tub/shower surround. If so... I prefer the vent in the ceiling within the tub enclosure. It's a fine place for a vent/light combo. It's best to have them controlled with a timer switch. Turn the switch ON and the shower light and fan turn on. Turn the switch OFF and the light turns off but the fan runs for a preset time, 10, 15, 20 or 30 minutes as chosen by you, then the fan turns off automatically. Then have bathroom lighting in the bathroom itself. Sconces on each side of the mirror, or ceiling lights. Depends on the size/style/layout of the room. Ventilation should be functional, it's best to have it as close to the source of moisture as possible. Lighting should be functional, ie, is it general room lighting or makeup lighting; eliminating facial shadows at the mirror, etc.

Yes! A bath fan thread. Most important is the ductwork. Insist on well-sealed, rigid metal pipe but a short flex takeoff from the fan can be good practice too. In cold climates, pitch the pipe to the exterior and use R3 to R8 insulation to prevent condensation drip. Use cape or butterfly dampers just inside the exterior wall for better blower door results. Consider 6" pipe for difficult runs and better performance or a jumper duct that passively supplies make-up air from a neighboring room. I just did a jumper duct in my personal bath reno with the supply grill right behind the toilet. It performs really well for that and my tiny bath with notoriously long hot showers. Panasonic whisper fans are among the most recommended and I think it's worth going out of your way for the best models. Integrated LED and 3-speed adjustment are particularly nice features. Broan has been stepping up better offerings too. Be sure the fan is well sealed to the ceiling opening. This important detail is commonly missed as it falls through the trade cracks. Timer delay wall controls seem best suited to effective bath ventilation.