I would highly recommend you look closely at the actual light from the Hue bulbs (of various flavors) and see whether you like the light quality. Getting a test kit is possibly the way to go. @RyanAtSense just linked to an Amazon deal here
but remember these are the color bulbs and not all bulbs are created equal. That said if you start with the colored ones and you can live with the light quality in “white” modes then you’ll be more than happy with the “white” ones if you add them. If you dislike the “white” modes on the color bulbs then you can tread more cautiously in your adoption but eventually use the colored bulbs for alerts and whatnot, which I find very useful. Toddler + red mode seems like a perfect match!
With the Hue app you add bulbs and you can then control (switch/dim) the individual bulbs from Sense without having to launch the Hue app. You cannot do color manipulations though from within Sense. There are many options but I think Sense has struck a good balance with keeping the interaction simple. Details about the integration here
As far as the processor hit on Sense from the “smart” interaction, Hue is not like a smartplug in that Sense is not pulling a constant energy use datastream from Hue so it does not have the same impact on the Sense processor. It (periodically) has some impact but it’s minor compared to the smartplug load and not part of the “20 max”. Hue accounts for the energy load of bulbs and it’s quantified over time and this data is used by Sense as @kevin1 details here