I've been setting up and teaching computer skills part-time in northwestern Cambodia for about 8 years now.
Getting equipment to a remote location is an expensive and perilous task. Damage, theft, bribes, delays, fees, more bribes, and unforeseen problems will cause you more headaches than you can imagine. I buy my equipment locally from a seller I have built up a relationship with. Because I'm a repeat customer, he goes out of his way to make sure the computers keep running when I'm not there, which is most of the year.
Because Cambodia is one of the poorest countries in the world, the idea of spending $300 on a copy of Microsoft Office is unthinkable. That's enough to run a small household for a couple months. You can install open source alternatives if you like, but it might not be a necessity since the machines are chock full of apps.
Getting the lab running is frankly the easy part. Your lesson plan needs to take precedence. Teach skills that are commercially viable in the country, inspire them to learn more, and give a solid foundation of basic skills. I have former students that can directly tie their lessons to helping them find jobs later on. They then take these skills and teach others, which creates a virtuous cycle. Good luck!