Ah.
Ok, a few things:
White cloudiness can commonly be attributed to "bacterial blooms". This is when bacteria and other micro-organisms that naturally occur in the water multiply in vast numbers. This happens a lot in new tanks because there are excess waste chemicals (ammonia, nitrite, etc) in the tank, because there are residues in the tank that the bacteria can eat, because the water parameters are often very unstable, etc. Basicly - a bacterial bloom is a sign of an unstable tank.
Changing the filter over, lock stock and barrel, will have lost you all your "good" bacteria. These are two kinds of very special bacteria that live in the filter media (ceramic rings, sponges, etc) and perform a vital life-support function in the tank by removing ammonia and nitrites. These bacteria are so important that many people say fishkeeping is about looking after the bacteria. If you look after the bacteria, usually the fish will look after themselves.
Live plants, well rinsed ornaments and other items very, very rarely cause problems in the tank. In fact, live plants actually make the water more stable and a better habitat for the fish.
100% water changes simply add to the instability in the tank and won't help. They're only a temporary solution and every time you perform one, you have to carefully make sure the temperature, pH and hardness of the water you are putting the fish back into is the same of the water they came out of. Not only that, but you'd need to re-acclimatise the fish to the new water and this is stressful for them.
What water conditioner are you using? Some of the simpler ones don't do the full job and you can get ammonia spikes from using them as they break up a compound called chloramine into chlorine and ammonia . . . and then don't remove the ammonia! This can add to blooms and general instability in the tank.
The oily film is often there. It's just where any tiny oily residue in the tank (from your hands, etc) collects at the surface. If your filter is close enough to the surface, the water movement should disperse the oil and make it less noticeable.
Right now, the best thing you can do is to get a test kit for ammonia and nitrite at least, and nitrate, pH and KH/GH if you can. You can do as many water changes as you want and talk to your fish shop all you want but without the ability to do daily tests on your clearly unstable tank, you're flying blind.
Do the tests, change the water if you need to (i.e. if the levels of ammonia and nitrite are above zero and don't do 100% changes) and try to leave your tank alone for a bit. It needs time to settle down now and the only thing you really need to be doing is those water changes. The more chemicals you buy or things you add/remove, the more unstable the tank will be.
Good luck.