Are there any "how to" guides

We don't have a very good API/Hook documentation yet. However, I will be glad to help you out if you give a little more details on what you are trying to accomplish.

The following code snippet uses the "gforms_post_submission" hook. This hook fires after every valid submission (after validation has taken place). You need to place this code in your theme's functions.php file. You can then modify it to save the date in your mysql database.

add_filter("gform_post_submission", "save_date", 10, 2);
function save_date($entry, $form){
   echo "date: " . $entry["date_created"];
}

As far as your second question, the advanced fields (email, phone, etc...) do have validation that enforce data to conform to the right format. However, we currently don't have support for custom validation, so you won't be able to add your own rules. We will build that in eventually, but it is not currently supported.