$5.95 + $108.40 "expert installation" I will happily install them for $108 each!
I have one hidden under my dining room table to control the Sonos volume/skip/pause as needed.
Night light ones on each night stand to control lights and ceiling fans.
I even have one to control the up/down/fan on my kitchen downdraft after I burnt out the (not sold anymore) internal controller with a pan of boiling water. Fan is wired to a Z-wave switch, up/down motor is wired to 2 Fibaro RGBW controllers, powered by 2 POE injectors (one positive to go up, other negative to go down). All controlled via HE, not your everyday solution but it works great.
No. See the Zigbee mesh doc linked to above--it's likely to cause problems. If you already have the Hue Bridge, keep it. It can integrate with Hubitat through that. If you don't and want to use Hue Lightstrips for some reason, consider a way to make this and/or other types of Zigbee lights be the only devices on that Zigbee network. This is where the Hue Bridge comes in, though a second Hubitat would also work. If you just happen to not have any other type of Zigbee devices (motion sensors, contact sensors, etc.), then you'd also be good. Most people do, and the general recommendation is therefore to avoid this.
They're not officially supported, but there is a community integration:
I only have one LIFX bulb and don't currently use it, but it worked well for me when I did. Being WiFi devices, these eliminate the potential Zigbee mesh problem, but I wouldn't fill my whole house with these (or any WiFi device). The price difference from Hue--which, again, works quite well as its own system if you want my opinion--doesn't look significantly different. (I only have one of these because they have an 1100-lm offering.)
I haven't compared side by side, but a friend has the Sengled strips and I have Hue (he does also have Hue bulbs to compare). Hue does a wide range of color temperatures well, in my opinion. Sengled does best warm, I think around 2700K, though I like the 4000K strip output enough that it doesn't seem different from the Hue bulbs. However, it definitely can't get as warm as Hue. Hue may not be as bright at all colors but the strips are better than the bulbs in my experience--which I admit is a bit limited since mine are almost always at some shade of white. From a technical perspective, I see how Hue can be better: their lightstrip is a five-channel kind (RGB plus warm and cool white), whereas Sengled's is four (RGB plus white, presumably warm).