Need help for making dynamic choice

Hi,
            I am struck with a problem. The Problem is:
I am attaching a screen shot with this mail. 
Well what my requirement is that:
1)                          When I select the Drop down control which shows
the content as "TEST" or any other values from the same drop down, its
corresponding Element values from my input xml should get populated in the
corresponding right hand fields like "Name, Amount, Type and Tax." 
2)                          The drop down will have 5 values only, and if
the input xml doesn't have these 5 values then it has to show in the drop
down as "# - UNUSED". And also any editions done from the right had text
boxes, the corresponding values should get updated in my output xml.
 
My input xml can look like is:
                    <element id="1">
  <                     <name>test22222</name>
                        <amt>10</amt>
                   <type>xxxx</type>
</element>
                <element id="2">
  <                     <name>test44444</name>
                        <amt>20</amt>
                   <type>xxxx</type>
</element>
                <element id="4">
  <                     <name>test33333</name>
                        <amt>30</amt>
                   <type>xxxx</type>
</element>
The element by name "name" should get displayed in the drop down box which
is at the left hand side and only 5 values need to be displayed in the same
drop down box and as we can see in the above xml, id's 3 and 5 are missing
so for such case, the drop down should show as "3 - UNUSED" and "5 -
UNUSED". And also when I select any value from this drop down, based on the
attribute "Id" chosen, the elements name, amt and type's should get
displayed in the right hand side controls and any editions done to it, the
same fiels of the xml gets updated and if any editions has done to "UNUSED"
values of the drop down then the corresponding "element" entry need to be
inserted in the same xml.
 
Please give me the solutions to these issues since this has come as
workstopper to me.. Please need help.
 
 
Regards,
Anjali