Ok, I will do my best to answer what I can.
1) I can't remember the bond for the 206 but 6000 Pula (this is for botswana) sounds about right, and the bond for the Van was around 10000 Pula. I think! Its not a huge amount in overseas terms.
The bond is not taken out of your paycheck. You basically "Work it off". If you leave before your time then you are required to pay the remaining amount.
2) Unsure of the eye things, I have no problems with mine.
3) Unsure about Nam. I would say go with the 270, but mention you have an extra 90hrs in a sim.
4) No real difference in going via road or via plane in terms of getting your visa. Maun is a tourist town and have hundreds of them arriving every day at the airport. Same with via road.
5) As long as your licence is valid, then it will be converted. You would probably be better off going for the FAA one. Not sure of the FAA examiners. Pretty sure there is none in Maun.
6) Wilderness Air has increased their minimums for ease of permit issue. If you have a truly exceptional CV they may take lower than that, but for the most part they are higher.
Don't even bother with Zim. They only use local pilots from there. Zambia has a 1000hr limit on expat pilots so most of the Zambia pilots go from the Botswana base to fly up there.
Nam I am not too sure about. I know they were having issues with getting expats work permits, and were looking at doing the whole 1000hr thing as well. I don't think it acutally happened but it is tricky to get in there. Can't hurt but try though!!!