I have been on two trips as a member of staff both of which were a two week duration (India & Morocco). They involved…. acclimatisation to the country, voluntary work, expedition such as trekking the tea plantations or summitting Toubkal, R&R. A 4 week stint would be pretty tough, the kids i’ve worked with have just about had enough at the end of the 2 weeks.
Students fund raise in various ways, bag packs, sponsored walks, washing cars at school, sweet stalls, race nights, curry nights etc. If some students are struggling we will help them out in school where we can. Due to the demographics of the school we find some parents just pay for the trip whilst others fund raise the entire amount. My observation would be that the students that fund raise get more from it.
We use a company called outlook, very good and very professional. They have an ops room in the UK that is manned 24/7, they also have people in country that they can call on if they encounter any problems. We had a schedule and were required to check in on certain days. Other safety measures included a very comprehensive first aid certificate and a direct contact number for a doctor. As well as myself and another staff member from the school the expedition was lead by a member of staff from outlook, usually somebody that is ML qualified.
Most of your questions will be answered at the presentation evening but as suggested try and find first hand information such as blogs etc.