Slightly confused about custom ROMs and radio ROMs

[jonnythan]

I'm using Juicy 2.5 and keep hearing people talk about the Verizon radio ROM.

Is that something that's included in Juicy 2.5 or something that I have to apply separately? Is the Verizon radio ROM compatible with Juicy? Does it break anything? Is there anything else worth knowing about it?

Also, I've downloaded the radio ROM but I'm not entirely sure how to apply it. Do I just run ROMUpdateUtility.exe? Do I need ActiveSync installed on the PC I'm using to apply it?

The radio ROM thread also says "be sure to back up your MIP settings such as aaa/an auth key and such." Can someone explain this?