Is there a way to make subscribers fill in the first name, last name, phone number, etc.?
You will probably need to provide an override for "newsletters:email_subscription_block" given the file newsletters:email_subscription_block/subscribe.tpl doesn't allow for adding more fields before the "submit" button is displayed. The code should look similar to:
{hook name="newsletters:email_subscription_block"}
Thanks. I'll look in to that.