Does NER work on large documents around 1500 - 3000 words or so?
The size of the document on which NER is run shouldn't be a problem at all, a standard NER system scans the document sequentially and just marks any entity it finds.
The size of the entities to find might be more of an issue, because typical NER systems rely on the previous few words to detect the boundaries of an entity. If the entity spans a large sequence of text, it's harder for the system to detect where it ends. In case it actually causes a problem with your data, it might be possible to specify exactly which features to use in the CRF model (this depends on the implementation I guess).