Do all 4 halo rings comes in one purchase?

Thank you for your question. This order will come with 4 halo rings and one Bluetooth box. You can check the details on the page.

Do these come prebuilt or not

Thank you for your question, these just come with the headlight halos, not including the headlights.

Is this for top and bottom or just top? Question also for the RGBW

Thanks for your question! It's for top and bottom,and also apply to the RGBW

Do these just flow or can they stay one color

Thanks for your question!Yes, not only it can flow ,but also stay any color, as it has color wheel

Can I purchase the controller box separately

Hello, you could purchse Bluetooth control box separately but please make sure it will work for your light bar, order link, https://www.vividlightbars.com/collections/accessories/products/chasing-bluetooth-remote-controller-for-chasing-led-halo-lights

How do you put them in the headlights

you need take the headlight apart, then install the halo on headlight outline