Congratulations on your new job!
As far as post-mortem care, you'll just follow your hospital's policies on that, so no real need to look up anything.
Because of their treatments, many of your patients will be anemic, at risk for infection and at risk for bleeding. So you will be shown the precautions in caring for these people. STRICT handwashing, before and after patient contact, is of utmost importance. The unit will have additional specific precautions you'll learn in caring for those at risk for infection.
Because of their low blood counts, fatigue, risk for bleeding, and spread of the cancer (to the bones or brain, for example), these patients are at high risk for injury; so as a CNA you'll be responsible for assisting them out of bed, to the bathroom, ambulating, etc. You'll need to be careful in assisting them in moving about or positioning in bed and very patient with them as well; many move very slow because of pain or other issues.
You'll need to know how to take accurate vital signs, and report them to the nurses in a timely manner. Be aware of patients who've had mastectomies, dialysis grafts, or have IV lines or ports; there should be signs posted in the rooms if you cannot use either (or both) arms for blood pressures, but sometimes that is overlooked so it is a good idea to ask the nurse
and the patient where you can take BPs. Also know how to take a manual BP.
Be aware of fevers in your patients. If you take a temp, ALWAYS take a full set of vital signs, including BP. If a patient has chills, don't simply get them a blanket but take a full set of vitals and report it to the nurse asap. That is a sign that their temp is going up and they could be going septic. You'll be doing alot of vitals in any case because of treatments, transfusions, etc.
I'm running late this morning; that is what I can think of off the top of my head (and having just woke up lol) It's a fast-paced unit, and many of these patients are critically ill. You'll learn alot. Good luck