Haha the hiring period isn't a myth. Its a good general idea to be in town around that time.
Some get hired earlier, some get hired later. It purely comes down to when the companies need new guys. A few of the guys are leaving later now so the hiring is probably shifting to later. Although leave it too late and then you are trying to do training in the full swing of the season with full planes!
I wouldn't be too concerned about Ebola in Botswana. Nor the tourist industry because of it.
Most of the tourists that come to Botswana tend to have money and a little common sense. The camps are pretty removed from that sort of thing.
The main ones that might take a hit are the scenic flights from the overland buses.
The core business will still be there.
As for getting a gig with less than 500hrs.
You need significant time on one of the types (and not the C172) or, with one of the companies, be a good looking female with any sort of hours.