Flashing Nethunter on Oneplus3??

Ok so i wanted to install nethunter on my oneplus 3..

So i had a few questions.. Ill be grateful for your help...

1. Does each rom has its own kernel??
2. Is nethunter a rom or you patch it onto an already existing rom??
3. There is a nethunter kernel for oneplus3.. So can i install that on stock rom or do i need a custom rom for that...
4. After i patch the kernel.. Do i patch nethunter arm img onto stock rom or as a new multirom or onto a second custom rom???