sorry,i meant to reply on your other thread,but its been a busy couple days for me.
the rom flash will not affect your verizon flash,it does not change those settings. calls and sms should still work fine after the flash,we will just need to figure out how to restore your APN settings,as ICS does not allow the install of APNs by 3rd party apps(wich would make it easy

). restoring APNs should make data and mms work on the new rom.
making a backup shoud preserve the current apn settings,and restoring it if you cant make it work on a different rom should make everything functional again.
you can use something like
this app to backup your current APN settings.
if nothing else,we can read that file and know what your current,working APN settings are.
on the new rom,APNs will possibly be able to be manually entered in settings/mobile networks/access point names.
its hardly ever an issue entering new APNs on a gsm device,i guess since its common place for gsm phones to move around to different carriers,but cdma phones are funny. really well just have to give it a try and see