1) mailwizz-php-sdk needs some modifying for it to work, last time we checked it did not work with latest MW version, so that is probably couple of hours for tweaking it to work
2) Documentation can be something simple like 2 pages document how to use API with couple examples, but it can also be very bgi document covering every detail of API, all usage options etc, so I need to know which one do you need
Cheers