Besides the edit part to show which thumbnail comes online it sounds pretty much like Expressoft from
http://www.neowise.com/
similair gallery build.
<html>
<head>
<title><#IndexPageCaption></title>
</head>
<#IndexPageBody>
<center>
<h3><img src="imageslogo.jpg" width="350" height="150"><br>
<#IndexPageTitle>
<br><br><#TopNavLinks><br>
<#IndexTable>
<br><#BottomNavLinks><br>
</center>
</body>
</html>
similair setup.
1 - how many colums pr. gallery page
2 - how many rows pr. gallery page
3 - width of thumbs
4 - hight of thumbs
5 - how many images pr. page on frontpage
+ some extra features.