I searched this document for
build.xmland no hits...
I got the answer to one of my questions, however:
The Seam Project wizard generates projects like Eclipse WTP style in order to utilize Eclipse WTP features and to
have a correct classpath. To be more precise it generates one project per artifact.
WTP is very limited in what project structures it supports.
A future release of JBoss Tools will generate an Ant build, but this has not yet been implemented.
I've been looking around for the same thing. I'd encourage others to go vote for the JIRA issue Gavin entered for it:
Someone has already taken a stab at making their own build.xml and attached it to the issue if you're interested. I haven't tried it out, but it's probably better than starting from scratch...