Good questions and answers are published here. So this is a good place to check before contacting us.
Difficult question to answer. From a cultural perspective seasons are not a limiting factor. Certainly major celebrations would be worth mentioning -Meskel, Epiphany, ... Contrary to creatures of habit, the rainy season (July-Aug) is the best time to observe or take photo graph. If volcanoes in the Danakil Depression is your cup of tea. Then you'd want to be here Dec-Feb. Wildflowers in the countryside are spectacular late September.
Compared to neighboring countries mobile INTERNET is good and steadily getting better. However much slower than the US, Europe, etc... If you just need email access, Ethio Telecom mobile internet is adequate. Especially if you can create a hotsopot to share with your PC. On the otherhand, if you need to regularly upload/download large files (10MB+ / 50MB+). Then adopt a reputable WiFi spot or buy a WiFi modem from Ethio Telecom -the sole service provider. By the way, service works along all the main highways.
Theoretically, yes. In this market, however, it would be more efficient if you came to see the market and players before making sales calls. This is a big ticket item and a long sales cycle. Make sure you are willing and able.
Yes and no. Duty free importing of house hold goods are not allowed any more. However a one time exemption is available to legal residents of Ethiopia when pre-approved through your local embassy and foreign ministry. Also one can import select capital equipment duty free (excavators and buses) or everything else if you carefully complete investment protocol.