That is not the intention of the system. Pigskin is intented to maintain the version of an application on a user's computer.
You will hopefully save a good deal of time by using Pigskin instead of making a versioning system from scratch. If there is a feature that you need that Pigskin doesn't do, you can put in a feature request or modify the source code.
The Pigskin client is made up of two parts -- a "container" and a "module". The module is updated automatically by the Pigskin system when the client connects to a server. Each module version may have different options, so you can't determine which options are available to you until you connect and deteremine the version of the Pigskin server.
It is not necessary for an application to exist on a machine for Pigskin to "update" it. When the client connects, it will download all of the files from the application directory on the server. Naturally, if you store all the files needed to run the application on the server, then the application will be deployed by running Pigskin on the client with the appropriate options. If you have a way to automatically invoke the client on multiple remote computers (via a telnet session or a Windows logon script, etc), then you can use this method to automatically deploy applications. Of course, you will have to find platform-specific methods of overcoming obstacles such as user priveleges and modification of settings (such as modifying the Windows registry).
Absolutely not. Pigskin is a Java program that can be run on any Java platform to update any application. However, applications written in Java can interact directly with Pigskin classes if desired. See the documentation on using Pigskin as a Program for more information.
Basically, if you can use Pigskin as an application and it works for you, then you should do so. But if your application is written in Java or has a way to directly invode Java code, then you may be able to use the Pigskin classes and have a little more control over the update process.
I will avoid descending into a discussion about the performance of Java in general. In the case of Pigskin, there is little processing involved and the system will spend the vast majority of the time waiting on the network. I don't believe that a non-Java implementation of Pigskin would be significantly faster.
Pigskin is implemented in Java so it will be supported on a wide range of platforms. Java also is very convenient when writing network applications. There are no plans to port Pigskin to other platforms because at this time I don't see the need to do so.