im not sure how metal models are new to you since a lot of
gw miniatures were metal.
they started to change that and a lot of metal models are now finecast.
if you purchased finecast miniatures and are talking about those:
http://www.games-workshop.com/gws/content/article.jsp?aId=16600008a
some people like it,others hate it because of quality issues
superglue works fine for metal and finecast miniatures.
you can go here:
http://www.games-workshop.com and look at each miniature and what its made of