No, do not switch between get and post.
on the first page create your form as:
[html]<form name="form1" method="post" action="">
<input type="text" name="firstname" id="firstname">
<br>
<input type="text" name="lastname" id="lastname">
<br>
<input type="submit" name="button" id="button" value="Submit">
</form>
[/form]
On the second page, create any new text fields you want, and create hidden form elements with the same name as the form elements from the first page:
<form name="form1" method="post" action="">
<input type="text" name="city" id="city">
<br>
<input type="text" name="state" id="state">
<br>
<input name="firstname" type="hidden" id="firstname" value="<?php echo((isset($_POST["firstname"]))?$_POST["firstname"]:"") ?>">
<br>
<input name="lastname" type="hidden" id="lastname" value="<?php echo((isset($_POST["lastname"]))?$_POST["lastname"]:"") ?>">
<br>
<input type="submit" name="button" id="button" value="Submit">
</form>
the hidden form elements are set to capture the posted values from the first page, these values will be reposted with the form on the second page.
In the insert record behavior, you just need to bind the form elements contained on the second page.