Hello,
I taught Spanish in another language school here in Pristina so I am also familiar with Cambridge school, it is the largest language school in Kosovo.
I would advise you first of all that you make sure how much are they going to pay you per month. If you work for an international organistation Kosovo is very cheap however, if you are getting a local salary it is highly unlikely that you will get over 400e per month, which is barely enough to live here. For example, you can find a shared appartment for about 150-200e per month, or a studio flat for 200-250; food in supermarkets cost pretty much the same than in europe (which for Kosovar standards is very expensive).
Also, you do need a residence permit to legally work, you do not need visa to visit Kosovo nevertheless if you are intending to stay over 3 months I would advise you to apply for it.
Since you are going to live in Prishtina, just to let you know, there are watershortages every day at lunch time and from 11pm to 5am (another thing to think about before comming).
If you would like to contact me my email is: erica.riosforcada@gmail.com