Nobody can answer your questions about Ill/Rad better than Local_Man. See his guide: http://boards.cityofheroes.com/showthread.php?t=141225
Take a look at my Illusion/Radiation guide, linked in my sig. If you haven't read it yet, I strongly suggest you do. The guide includes a discussion about the benefits of APP powersets with Illusion. It has a couple of Perma-PA builds, and down near the bottom of the thread, I posted my personal Perma-PA build, which is very, very effective without being outragiously expensive.
Spectral Terror is your best AoE control. If the only thing you were going to do is walk up to AVs standing there by themselves, with no other foes around, and fight the AV by him/herself, maybe you wouldn't need Spooky. But Spooky gives you perma AoE control plus a a nice ToHit Debuff. I would never leave out Spectral Terror. Besides, the power can take a set with a 6.25% recharge or a set with 5% Recharge.
As for Radiant Aura . . . why not slot it up with Doctored Wounds for the 5% Recharge? That heal is very nice to have. Even with a Perma PA build, you will occasionally get hit with AoE or might draw a little aggro when PA drop.
As for the Ice APP . . . it is my second favorite, but I like the Fire APP a little better on my Ill/Rad. A little more damage plus a fast AoE attack with up-front damage. The Ice APP's strength comes from 2 AoE damage powers and Hibernate, plus a defense based shield. The Blast is the second best blast among the APP sets, but Fire adds more damage. The -Speed and -Recharge in Ice will have almost no effect on an AV, since AVs have high resists to most debuffs. (Don't forget you already have some pretty good Slow and -Recharge in Ling Rad.)
EDIT: Wiccania snuck in while I was typing my response. Thanks for the referral.
LOCAL MAN! The most famous hero of all. There are more newspaper stories about me than anyone else. "Local Man wins Medal of Honor." "Local Man opens Animal Shelter." "Local Man Charged with..." (Um, forget about that one.)
Guide Links: Earth/Rad Guide, Illusion/Rad Guide, Electric Control
Hadn't had a chance to read local man guide yet,Im unable to get on for long periods of time atm. I had a build that I made with fire instead of ice that was done before I started playing my Ill/rad. Was going to post it just to see what others think, but for some reason it won't let me add attachments. Not sure what it isn't letting me, I've added them before, but it saids I can't now.
I've been working on a build for my ill/rad in hopes of being able to solo AV's with him. I've got several different builds done that gives me perma PA and some nice bonuses. But I was wondering about a few power choices. With me wanting to try and solo AV's do I need spectral terror? Also what about the heal power, should I slot it up just incase if I get some aggro or just carry some respites for emergency? Last thing I was wondering is about the epic power pool. I kinda like the ice set. But I've got several diff. builds where I've choosen diff. powers from that set. First of all is ice even a good choice for fighting AV's? If so what powers from that set should I take? Just was curious if the -spd and -recharge from the set along with the dmg. it does would make the power choice worth it. Thanks for any and all help and info. I know it would be best for me to post a build but I just have to many builds I'm trying to decide between atm, so If I could get some opinions on what you all think then I can choose one or narrow it down to a couple atleast so I can post it/them for critique. Thanks again