Before leaving Goma, you might want to consider getting a police clearance and/or proof of residence. A lot of countries, tax authorities, banks and other institutions require such documents and it’d be a pain if you need to organize it after you’re already gone, especially if you need an original copy.
You or somebody you trust (power of attorney is not necessary) need to show your passport and bring one passport photo as well as $25 for each document to the mayor’s office, which is open from 9-15h Monday-Friday and from 11-14h on Saturdays.
They didn’t ask for a copy of my rent agreement but it can’t hurt to bring it along, too. You should get the documents the following work day.