Is there a way to remove that washed out yellow coloration on objects which have light shining on them when using HDR?

Try http://www.newvegasnexus.com/downloads/file.php?id=34868 without bloom friend..

That just adds to the bloom/hdr effect. I'm talking about in the vanilla game.

There is colour correction on ES that helps with the "wash out" look of the game, now about tunning the HDR i can't help you there..