Yeah, ignore what the medical student wrote (which should be a standing rule because med students don't know anything) and listen to what Splik said. Here are some of my preferences:
EtOH- main thing is going to be history (amount, hx seizures/DTs, which ideally needs to be verified by collateral) and social support (ie, can someone reliably give the patient his or her benzos). I'm not a huge fan of adjunctive/non benzo treatment, but gabapentin can be good as a maintenance medication as well. And why is your colleague doing a several week/month taper for EtOH withdrawal? You can safely taper someone off in a few days.
Benzos- for really bad cases (again based on history) you can admit briefly just for safety but ultimately they should be transitioned to librium or klonopin (because blood levels remain steady) and tapered off over several weeks as an outpatient. Most cases of pure benzo tapering can be done as an outpatient, as Splik mentioned.
Opioids- Opioid withdrawal is not an inpatient issue UNLESS its precipitated (when COWS isn't done correctly and Buprenorphine induction is started prematurely... or the patient decides to take Revia after shooting up heroin- saw this twice in a month as an intern). Again, why is your friend doing a slow week/month long taper if he/she just plans to detox the patient anyway? The literature from high impact journals specifically shows that this is NOT effective and leads to relapse. If the patient is not a candidate for maintenance treatment or you are in a setting where you can only detox, this can be done over 5 days using bup+symptomatic treatment.
In any case, treating withdrawal is the easy part... I would be hesitant to take a patient with a severe substance problem off of any maintenance medication (after rehab) unless he or she demonstrates enthusiasm for going to meetings/sponsor/12 Steps or some other continued support system with focus on sobriety. Obv the 12 Steps are the most established and thus it's easier to ascertain level of engagement, enthusiasm, commitment to recovery than some of the other things people do.