Crash and error report to developer [from user perspective]

Question

I have some questions regarding whether to crash or report errors to the user. We are developing a web site and mobile clients in which we allow our users to report any bugs and crashes through e-mail. We require the user to send the e-mail from their e-mail account, so they can be identified. Here are some questions regarding it:

1. We used to send the last stacktrace of java when user presses "send error report" button. As it has only technical details that user may not understand or care about, is it necessary to show this stacktrace to the user?

2. What if the user is concerned about privacy? Is it good practice to collect stacktraces of crashes and unusual behavior keeping user's privacy in mind? If it's not what are the other alternatives?

3. For mobile devices what if the user wants to send an error report to the server but there is not any network connectivity, is it necessary to have a record of this type of common errors that is not related to application?