To answer your questions:
1. No, there really isn't an nVidia equivalent that I'd truly recommend at this price point. Unless you wanted a $300 GTX 470, then Radeon has the better offerings with DirectX 11 right now, and for less.
2. I honestly think that the R5770 Hawk Edition isn't any thing special. Sorry MSI, and I'm running their card and motherboard right now, but for as much as you pay for it, you give up a display output, and OCing a 5770 doesn't really help that much, or at least in my experience it hasn't.
3. Yes, there are a lot cheaper 5770s, but nothing really better that's cheaper at the same time. I can recommend the HIS IceQ 5770 (more expensive but better) and the HIS H577FK1GD (about the same but cheaper) if you really want a 5770.
4. Yes, there is a better card at $210; the Radeon 5830. The "HIS iCooler V 583FN1GD" to be more exact, it has full 256-bit memory, and is relatively in-between the 5770 and 5850, although it leans towards the 5770 side of things.
http://www.newegg.com/Product/Product.aspx?Item=N82E16814161327&cm_re=Radeon_5830-_-14-161-327-_-Product
An
excellent card in my opinion.
5770's
http://www.newegg.com/Product/Product.aspx?Item=N82E16814161333&Tpk=iceq%205770
http://www.newegg.com/Product/Product.aspx?Item=N82E16814161338&cm_re=HIS_5770-_-14-161-338-_-Product
5830
http://www.newegg.com/Product/Product.aspx?Item=N82E16814161327&cm_re=Radeon_5830-_-14-161-327-_-Product
5850
http://www.newegg.com/Product/Product.aspx?Item=N82E16814161330&cm_re=Radeon_5850-_-14-161-330-_-Product
^Just to show HIS's excellent reviews on NewEgg.
Here's a benchmark of the 5770, 5830, and 5850:
http://www.tomshardware.com/reviews/radeon-hd-5830,2564-5.html
Yes, I'm sure you see the 4890 in there, but I personally would go with the 5xxx series over it, just because of the relative future-proof DirectX 11 support.
From my earlier experiences, HIS has excellent customer support; at least when I needed it with my earlier cards.
There you have it. Good luck with your card shopping.