This means that the form data is not encrypted before transmission. It is possible for the form data to be intercepted as it travels across the Internet. See the section on Security for more details. See the section on Security for more details. Depending on your email service, it should arrive in your mailbox within a minute or two at the most.
Delays are uncommon, but can be caused by high network traffic or a busy mail server.
Well, yes and no. First, use the Form Wizard to create a form template. This will give you the hidden fields you need. Second, copy and paste the hidden fields into your existing form. See Form Basics for where to paste the fields.