2) I also tried it with my own product. I apply the tycho-jnlp-plugin in  a pom 
which also materializes the .product. As I sign the jars myself I don't get the problem like in 1), but
I get a problem running .jnp on my Mac. 
<message>***WARNING: Display must be created on main thread due to Cocoa restrictions.
This is however not generated by tycho.
Additionally I am generally puzzled by which properties to define in the .jnlp and which one will be picked up from the eclipse.ini / config.ini. Do all properties need to be defined in .jnlp? 
The pom for my project: 
<project xmlns="
http://maven.apache.org/POM/4.0.0" xmlns:xsi="
http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="
http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>com.netxforge.releng.products.netxstudio.cdo.jnlp</groupId>
    <artifactId>com.netxforge.releng.products.netxstudio.cdo.jnlp</artifactId>
    <version>1.1.8-SNAPSHOT</version>
    <packaging>eclipse-repository</packaging>
    <parent>
        <groupId>com.netxforge.netxstudio</groupId>
        <artifactId>com.netxforge.releng</artifactId>
        <version>0.0.1-SNAPSHOT</version>
        <relativePath>../../releng.tycho/com.netxforge.releng</relativePath>
    </parent>
    <build>
        <plugins>
            <plugin>
                <groupId>org.eclipse.tycho</groupId>
                <artifactId>tycho-p2-director-plugin</artifactId>
                <version>${tycho-version}</version>
                <executions>
                    <execution>
                        <id>materialize-products</id>
                        <goals>
                            <goal>materialize-products</goal>
                        </goals>
                    </execution>
                    <execution>
                        <id>archive-products</id>
                        <goals>
                            <goal>archive-products</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
            <plugin>
                <groupId>org.sonatype.tycho</groupId>
                <artifactId>tycho-jnlp-plugin</artifactId>
                <version>1.0.1-SNAPSHOT</version>
                <configuration>
                    <jnlpFile>${project.build.directory}/repository/netxstudio.jnlp</jnlpFile>
                    <target>${project.build.directory}/repository/</target>
                    <skip>false</skip>
                </configuration>
                <executions>
                    <execution>
                        <goals>
                            <goal>jnlp-file</goal>
                            <goal>sign-jars</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>
</project>