How do you query and explore ENCODE data? I am looking for a modular way to query data from ENCODE. 

For example, I would like to get CHiP-seq or similar tracks for a specific cell line. What's the proper way to do it? 

Finally, is there an API to do it?
I don't know whether there is an API, but ENCODE's website does provide an interactive data matrix where you can filter data based on assay and sample type, place data sets in a "shopping cart", and then proceed to "checkout" to download the files of interest.