Call to undefined function project_get_related_tids_map() in /.../project_solr/project_solr.module on line 266

This stuff is all a D6 hack. There's this notion in D6 that certain vocabs are "related" to only certain project types (using that monster D6 "Projects" vocab where the top-level terms are project type and the sub terms are categorization for each type). Basically, this lets you configure certain vocabs to only appear on project nodes with a certain top-level term.

None of this insanity is needed in D7. Since each top-level project type is a separate node type, each can just cleanly have its own vocabularies. So, instead of anything related to this mess, I think you just want to look at each of the vocabs on each project node type and Do The Normal Thing(tm). Maybe project_solr doesn't actually have to do anything at all here, and the default solr indexing will Just Work(tm)?

tag

Taking this.

Yep, it is unnecessary. I got project taxonomy filtering working on the main site search without this code, which I deleted.