Concerning the resizing, when using Lanczos use Lanczos4Resize (since version 2.5.5) which results are a little sharper. But there's an interesting method on Doom9, called Integrated Image Processor, which uses a combination of different resize-processes to avoid too much blur.
And for noise reduction check out the RemoveDirt-filter.
One more link regarding the removal of chroma-artifacts.
And I still think you should get rid of those halos. By the way, do you know why the stairsteps occure? ARE you deinterlacing? Or are those things already present in the raw capture?