what happens if i download and install this OS on top of Android
This is an Android phone, what does an iOS I dearly love to lose. But I don't know how to go about installing the Firefox OS on top of Android. Does it create its own ROM or do I need to use something like the rOM Toolbox to create a new ROM? Ti a
Wšykne wótegrona (1)
At this point, I do not recommend trying to replace Android with Firefox OS on a device important to you. Development for smart phones has stopped. However, to get a taste of it, you could check out the Developer Preview app for Android (replacement home screen launcher):
https://hacks.mozilla.org/2015/11/firefox-os-2-5-developer-preview-an-experimental-android-app/