Center duplicates markers and adds others and distance

www.compuboat.com/index.php?option=com_yp

I have searched the board and Mapki, as well as other tutorial sites
and have not found the answer so now I am here.

1. I have a dynamic XML passed back that I am trying to only update
those markers I haven't used already. What is happening is that it is
duplicating some of the markers and adding those anew to the list. This
is my main issue. I believe if I can check the markers on the page
before placing them I will be able to avoid showing the extra markers)

2. I have a SQL statement that I have been using to order the sort by
distance (see
http://groups.google.com/group/Google-Maps-API/browse_thread/thread/efdaba42d3c22cb9/0747fc4c5f9ec330?q=radius+&rnum=4#0747fc4c5f9ec330)

I would like to limit to an area of 1 mile (maybe 10) depending on the
area. does anyone have an idea how this might work?

My last question which is a part of number 1. Is the array that I have
grabbed via the XML piece still live in memory via the JS?

Thanks to all have come before me!

Darren