Where can I get replacement screws for the stand?

I don't know where to get an identical screw, but I found one that matches the thread and worked for me at Lowe's.

Will it work on 2010 mac pro with ati radeon™ hd 5770 card?

You'll need hdmi cord but it has hdmi capability so it'll work. Awesome monitor for such a great price.

Can this be overclocked like the catleap series?

I was able to overclock mine to 110Hz. I have the Catleap 2B series as well and that one runs at 120Hz. If you are comparing the two, the Catleap does not have a scaler so the response time is slightly better between the two. But, at 110Hz I do find FPS games are playable. What I like better about this monitor is the color control with the OSD (which the Catleaps 2B models do not have). What I like less about the monitor is the AG coating. I knew it had it going in and it is not as bad as I thought it might be. But, personally I prefer glossy much more (which my Catleap is).

Whick cable will i need to connect to new macbook pro w/retina display?

The Yamakasi Q270 Jupiter has available a HDMI port,a DVI port, a sub-D port and a Display Port.I use the HDMI port connected to a Lenovo Yoga 2 Pro laptop with an HDMI cable with HDMI micro on one end and standard HDI on the other end. It is a terrific monitor and I am very satisfied. However, I did purchase from Monoprice a new stand and took the unit apart to instal the new stand.