I worked on a renal unit as a tech in school. We had patients both on hemodialysis (special dialysis nurse would come and do that) or peritoneal dialysis, which the nurses on the unit could prepare and administer. You will be caring for patients with both acute (and know that there are different causes to ARF) and chronic (and perhaps acute ON chronic) renal failure, glomerulonephritis, acute tubular necrosis and other renal disorders, as well as dealing with electrolyte imbalances, HTN (kidneys don't work well or the patient may have too much fluid on board, hence the reason why renal patients can have a very high BP!), anemia, fluid imbalances, etc...Diabetics frequently have problems with their kidneys so that will be a common comorbidity with this population.
Medications may include antibiotics (but generally avoiding nephrotoxic drugs), anti-coagulants, anti-hypertensives, phosphate-binders, erythropoetic/hematopoetic stimulating agents (renal patients often get Epogen), insulins, diuretics, iron replacement therapy...then of course consider other medications that the patient may be on for other conditions.
This list isn't conclusive but should hopefully point you into the right direction. The unit I worked on also received med-surg overflow patients so we would see a wide variety of patients including post-ops.