Hi Sander,
could you please provide the versions of the product you are using. Apparently, if you are on 8.5.1 RAD have you checked the infocenter about the maven integration -
http://pic.dhe.ibm.com/infocenter/radhelp/v8r5/topic/com.ibm.etools.maven.doc/topics/maven_intro.html - this is a new feature as from v8.5.1 in RAD. We are still on 8.5.0 and are using the m2e + m2e-wtp plugins manually installed. The most important part to make the deployment to WAS WTE work is either to follow the recommendations for maven project configuration as described in the link above OR to use the maven native name conventions for the artifacts, however in this case only "Publish to server with resources on server" does work (otherwise you get NoClassDefFoundErrors or similar at publish time). And after version changes we have to make "Clean" on the server to get everything updated - we've opened PMR for this with IBM but we haven't got resolution yet.
As for import maven project - we've tried it only from SVN with the provided maven-subclipse-connector. Here we have the issue that if you try this from the Package Explorer you get some weird error, but if you try this directly in the SVN explorer view everything works, which is ok for us at the moment.
Hope this helps a bit,
Ilko