HI Arnold,
Answer to your first question is HornetQ is not a must requirement. HornetQ is used as a human task server wand Mina task is another aletrnative which is provided.
You can try furst default implmenttaion /installer provided and then proceed with Tomcat integration.
You should be able to do the JBPm 5.4 integration on tomcat with mina task server without any problem.
Thanks,
Ashish