I guess this is a design limitation of the LucidWorks solr app package. One thing you'd have to do to avoid losing data on restart is to configure Solr to store its data in HDFS. You might be able to do this by setting the solr_opts parameter in the appConfig:
Slider has to run the Solr servers on random ports because it can't control where they are started (more than one might be started on the same host). The next release of Slider will have an anti-affinity container placement option, so that might help. You should be able to connect to each of the Solr instances that Slider creates.