Call Template inside preceding-sibling

Question

I am a pretty newbie to XSLT (using XSLT 1.0). Couple of questions:

1. I am currently working on a scenario which requires me to invoke a call template from inside a preceding-sibling iteration Is there a way to achieve this?
2. How can I convert a Result tree fragment to node-set?

Example: <xsl:variable name="node-set" select="msxml:node-set($result-tree-fragment-variable)">

Upon debugging $node-set, I still see tree fragment and not a node-set

Please guide me.