Hope this helps Your code is fine, the only problem is that your Heroku application can't connect to any Solr host. If you're using the Websolr addon in Heroku then you should open a support ticket because this should be working. Otherwise, you should run this in the heroku console:
Sunspot Solr Search like Rails active record 'LIKE' search
With these it helps I did something similar lately and had to answer the same questions. My problem space looked like having two languages (so preferably two cores and maybe more for other search options in future), having to index data over several table and search/count facets, partly in hierarchical structures like product groups and hierarchical tags like car_brand/model/type/build_year. As far as I have seen sunspot works best (only) if you have relative 'flat' data, at best simply have to define for a single model which fields to use. The moment you need to combine several models into a single document for facets, it becomes difficult. (But since I didn't use Sunspot I can't really tell for sure). You can (and should) still use the rsolr gem for the communication with Solr. But if you use Sunspot in development, it is most likely working for you anyway.