1. The question mark symbol is handy when you need to know the details about a build configuration option.
2. It is a Crontab syntax that you can use for polling your version control system.
3. Yes, you can use more than one language, for instance you may have a go script and a Node.js script that you need to run in your environment.
4. It is a Unix environment that you are operating in and a lot of Unix commands are available for use like sed and awk.

5. A global property will be available throughout all the build jobs you add while a project level environment variable will only be available in the specific project you add them in. This is enabled by the EnvInject Plugin.
6. It is useful to see the command executed and/or the output of the command so that you can more easily debug issues that occur with each command that is run in the CI environment.
7. The...