I kinda got lost reading through the posts trying to figure out what you've resolved and what you still need to do, however here are a few pointers for PHP and forms...
1) a shortcut for echo is <?="VALUE"?> or <?=$var?> so to save the values of form elements you may use <input type=text name=input1 value="<?=$POST['input1']?>">
For boxes and radios you can do something like $SELECTED = (isset($POST['boxName'])) ? "SELECTED" : null; and then your input would look like this <input type=checkbox name=boxName $SELECTED>
2) To submit the form automatically the javascript is very simple, just include an onBlur or onChange event in the tag. <input type=radio name=conf value=yes onBlur="form.submit()"> where form is the name of your form. onBlur is used when the object looses focus and onChange is used when the value of the object is changed.
3) You can also include every possible element you might need and modify the type attribute. <input type=hidden name=derivedElement > will hide the input so if you have a radio button you can include onChange="document.formName.derivedElement.type='text'" This will now display the hidden element as you wish.
4) Most elements include an 'innerHTML' property which you can play with... so you may include sections of the form in a <div> tag and use javascript to modify the innerHTML of the div for example: <div name=divblock></div> <input type=button onClick="document.divblock.innerHTML='<input type=text name=textName>'"> will create an input when the button is clicked...
5) CSS can also be used to hide and display elements. <input type=text name=textName style="visibility: hidden"> will create a input that should not be displayed by default. but onChange="formName.textName.style='visibility: block'" will now display the element.
I hope some of this helped, reply with what you want so I can more specifically help you