1) Its not possible to change the install dir that JWrapper uses. The reason why is explained here under 'Why can't I change the master folder?':
http://www.jwrapper.com/faq.html
2) If you wanted it to be reliable you might need to launch another virtual app which then communicated with your app and launched an uninstall of your app bundle when your original app had completed.
When you launch your child virtual app JWrapper can handle the communications between them for you:
http://www.jwrapper.com/blog/archives/08-2013
Then when the first app goes down you can use the JWrapper APIs to uninstall the entire bundle:
http://simple-help.com/media/static/jwrapper/jwutils/JWUninstallApp.html#doUninstallOfEntireBundle(boolean)
3) You can email us for a trial license for JWCrypt. Using it is very simple, the following guide explains how (bottom of the page):
http://www.jwrapper.com/guide-jwcrypt-code-protection.html