Unless you can tell us more about the particular e-cig you have, there is no way to answer your question, at least the part about atomizers. There are
many different models,
some of which are compatible with each other. You may want to browse
through the WWV Illustrated Guide referenced in my signature.
Parts 2 and
4 describe and show pictures of most models.
Any e-liquid can be used with
every model. As for where to get it...peruse the list of
ECF Approved Suppliers – some of them specialize in
e-liquid, others in hardware.
All carry e-liquid. If there is an exception, please let me know; I can't think of any.