This is literally, word for word, copy/pasted from the website he linked to in the OP, and his response to your first question...
I am pleased to announce that I am now supporting the Nexus S 4G as well as the Droid. This ROM will be released alongside my Droid build titled "GPA17". Until then you can find it in "nightly" form in the following directory: http://wonderly.com/bb/CRESPO4G/ROM/BETA/ (choose the latest file)
Some features include but are not limited to:
180 degree rotation
Overclockable to 1.4GHz
Updated wifi driver
FLAC audio support
Native 3G tethering
Ad-hoc network support
Modified widget picker
There are also many performance tweaks and bug fixes which you can find change by change on my github. For those of you who run CyanogenMod, now that I support this device I have began submitting patches to help out. In the future I plan on supporting the other Nexus S variants (T-Mobile & AT&T) as well.
Upon initial install of this ROM, please wipe data and cache. When a new build becomes available, you will only need to wipe dalvik cache. For the best experience, stick with the kernel provided in my build, I assure you it performs very well. If you are interested in saving tons of battery life, downclock to 800MHz in the CPU Toolkit, you will see little to no difference in performance.
Sorry this post does not read well, I am sick at the moment and not in the proper mindset to write.
XDA Developers was founded by developers, for developers. It is now a valuable resource for people who want to make the most of their mobile devices, from customizing the look and feel to adding new functionality. Are you a developer?