All you need to open bank accounts in Ethiopia are copy of your passport and work/residence permit. Almost all banks provide similar services. Loans would be permitted if the expats are engaged in business activities. It doesn't take more than half an hour to open bank accounts in anyone of the commercial banks. I recommend Zemen Bank for its speed and courtsy. Though it has only one branch, it has got ATM machines in most of the commercial areas.
It is difficult unless you have a residency card/yellow card. If you have one it is easy. Just money and 2 photos is required. The ZEMEN BANK near the Rasidon Blu hotel bank ,however, will give you an account if you do not have residency but there is a monthly fee if your account goes under 25,000 bire. You will get a VISA ELECTRON card in all the main banks.