Need Help!!! with My crown vic

I bought a 2003 ford crown victoria p71 3 months ago. Ive already had to replace the intake manifold,egr tube, belt tensioner and battery. Then my cel came on for my cats, so i just did exhaust, i got all my cats cut out and an xpipe and flowmasters put in. I did this a month ago, Heres the problem ive noticed a white smoke coming from tailpipes and i thought it was condensation, so i drilled a couple of holes in my mufflers. My friend helped me do this and he said the smoke looks more like a light blue. Its only at idle, and it smokes harder with my a/c on, and also it happens everytime i take off from 0, but after i take off there is no more smoke. Its deff oil because since i have straight flow exhaust i can smell it whenever i drive with the windows down. My car has 97k miles and i just did an oil change 1000 miles ago and dont notice any loss on my dipstick. However i put my finger on the end of my exhaust pipe and its deff oil. Ive read into this problem already, but i want to make sure i dont take apart half my motor to go fix the wrong thing. Ive read up that its most likely valve seals, and that its a common problem with these cars because the cops left them on all day. But ive also been told it can be rings or head gasket, but if it was these two things wouldnt my car run horrible. my car runs pretty smooth and has all the powere there. I have n oclue so i figured i d get some opinions

Light blue smoke is oil getting into the air mixture. This is usually from a very minor oil leak pass the valve stems. You need to change the oil stem seals. There is a write up somewhere (I can't remember where it was I read it; try www.crownvic.net) on how to do this at home. You will need an air compressor and a spark plug adapter to keep the valves closed while you remove the old seal and put on the new one. And you'll need to remove the tappet so you need a valve compressor to remove that too.

Be sure to use a quality valve stem seal, better than the OEM.

Just so im clear are valve seals and valve stem seals the same thing? if not whats the difference, and are you sure its not rings or a head gasket? I have a specialty mechanic by me that works in the warehouse district with me. He said he can replace the valve seals for $400 not including the seals, and he also said while im in there to change the valve cover gaskets. Does this sound like a good Deal?