Can a user find out the feature set the build supports before downloading and using? (I'm unclear after going through old posts which CHDK features are available/missing for the SX130is.)
While you can try reading through the
"porting thread" for a camera, and you can check the
CHDK wikia page for that camera, there is really nowhere you can get that information that is 100% correct other than trying the port for yourself. This is an all volunteer effort and frankly, the documentation is far from perfect as a result. However, I think its fair to say that most ports with beta status provide all the functionality listed in the CHDK documentation unless notes otherwise in the above references.
Also, can I find out which developer(s) is working on the SX130is, for a question (if open to direct contact) and to thank them for all the effort for SX130is users.
There is no mechanism for assigning a "developer" to a particular camera. People, who typically own that camera and have the software skills, just work on the port and post their efforts. Its very informal. You can feel free to read through the forum "porting thread" for your camera and send a "PM" to anybody you think might be able to answer your question. Although for the benefit of the community, its generally preferred that you post in the thread for all to see and learn from.