To answer your first qustion, the answer is yes. You can place a submit button anywhere you want, actually. Whether it performs some action depends on whether the button is nested inside of <form></form> tags and what the "action" attribute is that you are sending the form data to.
I have no idea what your code looks like on your second page (the one that generates the e-mail?), but it sounds like all it is doing is accepting values being submitted from the page where the user is being asked to double check his data. Basically, if you want to go from the HTML form direct to what is now the second page (the one that generates the e-mail), simply look for a line in your HTML form code like this:
<form name="myForm" method="post" action="firstPHPpage.php">
and change it to something like
<form name="myForm" method="post" action="secondPHPpage.php">
Just make sure that your HTML form is sending all of the same values and "name" attributes that the second PHP form handling script is expecting. I made the assumption that you are using the POST method to send your values. If you're using GET, just change the line attribute to 'method="get"' if you need to.