WLQL to JBoss QL conversion

Hi,
I am working on migrating a WebLogic(5.1.0) app to JBoss 4.0.5GA.
Here my concern is that there are finders specified in the weblogic-cmp-rdbms-jar.xml which need to be migrated.

My questions are:
1. I understand that for every <finder> in weblogic-cmp-rdbms-jar.xml, there should be a corresponding <query> in the ejb-jar.xml, but i could not find one such in this application. There are no query elements in ejb-jar.xml

2. Can I specify an expression (?3 IS NULL) in JB QL corresponding to (isNull $3) in WL QL

3. Can I write only EJB QL in ejb-jar.xml, instead of writing JBQL in jbosscmp-jdbc.xml because the latter might cause dependency issues later as WLQL cause now?

4. Is there any help available in the net which specifies in detail about JBQL?

Please Help!

Also, is there anything else I need to take care of while migration?