At least with DVI you can be sure the screen is getting the exact colour info outputted by the video card, since it's a digital signal. Plus there's no need for using auto-adjust when using DVI (in fact auto-adjust isn't even available when using DVI), the picture is always lined up perfectly with the screen edges.
Having said all that VGA doesn't necessarily look any worse. You can connect the screen via both VGA and DVI at the same time, set the PCs output to dual screens and switch between them using the OSD, and I couldn't see any difference. However I would still always use DVI.
I use mine on brightness 45-50. For the first few weeks I found it too bright on those settings but you soon get used to it.
Contrast is always unavailable when using DVI on all TFTs. Not 100% sure why, I think it's because it's supposed to be controlled via the PC, but there often isn't a way of actually doing that. Nevertheless though, the default contrast setting is fine.
I suspect the orangeness is just like you say, that you're used to your old screen. My 2007WFP has a noticeably different 'tint' to my previous Samsung 172T (in this case the Dell produces much better colours whereas white was off on the Samsung).