Hi!
>> 3) I am not able to open the reports, the attached error is thrown in the jbpm-console. How to I start the report server?
I don't know if this will of any help, but in file <jBPM-installation-dir>\build.properties there is
# defines whether you want the birt plugin (for reporting) to be downloaded or not
# by default this is turned off to avoid having to do a rather large download
# if you do not download the birt plugin, reporting in the jbpm-console will not work
# put this property to true if you want to download birt as well
jBPM.birt.download=false
Have you modified jBPM.birt.download to true before running ant install.demo?