I hope you enjoyed your trip.
One question; where from do they bring the male figs with the wasp inside to hang it on these trees?

I think that I can safely answer that!
I actually did such a thing; string-hanging-caprifigs
on our San Pedro-type fig (back at the Med-Sea home).
(also plus further reading and getting somewhat wiser)

For one thing the (poor) male-fig-wasp never leaves
the host caprifig. HE just dies in-there after having
some fun with them females. The ferilized female then
goes out of the caprifig-eye in search for other figlets
to lay hers eggs. Going out of the caprifig, she brushes
againts the male-fig-pollen. Once inside the "other"
fig (again thu the eye) SHE drops some pollen on the
female-fig-flowers - WALLA - Caprification....

Short sigma flowers get fertilized and/or impreganted with an egg -
(somewhat) bad for the fig - (very) good for the wasp.

Long sigma flowers get fertilized but NO egg inside -
bad for the wasp - but good for figs and specially humans...

Above applies mostly to the Smyrna/SanPedro type figs.
Of course there are those famous "common" figs that can do without
the fig-wasp to set the fruit at all - lucky US.

great info Gorgi!

I am going to add that they have to hang the male fruits on all female fig trees because if someone has a large orchard there is a risk that not all the female fig trees will be pollinated. Additionally, they have to repeat the operation every few days by going around and hanging new male figs.

Also, keep in mind that a wasp can travel between 2 to 3 km's.

Lastly, they cannot keep male fig trees in the proximity of female fig trees because if too many wasps enter the female flowers the figs will have a higher ratio of fig splitting.

I guess I should stop there since I am spoiling everything...

Actually, fig wasps can travel up to 100 miles. You may find the article below from ~3 weeks ago to be very interesting reading. There are also some fun facts about African fig trees.

Here is a link that might be useful: Fig wasps travel further than any other insect

Satellitehead: thanks for adding this very interesting information.

My information comes from the Fig research center in Turkey www.erbeyliincir.gov.tr
Probably, the variety of wasps in Africa might be slightly different or the information they had at the Fig research center was outdated

Good point, this is very possible.

When we discuss figs, we also recognize that different climates probably trigger (on or off) certain growing and fruiting traits, which is why there seems to be great diversity of characteristics of the same breeds in different places of our countries.

I can only imagine that certain environments have caused the same for fig wasps, and when you add natural selection in with that, there is no telling how different the wasps may be, or may have evolved.

Could the following be the reason for not grafting male fig tree branches on the female fig trees?:
"they cannot keep male fig trees in the proximity of female fig trees because if too many wasps enter the female flowers the figs will have a higher ratio of fig splitting."

Satellitehead : I should add this quote from your link to add some context.

"Their wings aren't that strong and they are not very good fliers," says Compton. "What happens is that they get caught up in an air column and get swept along by the wind, which in this part of the Ugab river valley in the Namib Desert can gust up to more than 30kph [17mph]."

Therefore, the local wind conditions are helping the wasps fly further and I would perhaps assume that they have enough strength to fly 2 to 3 kms without the help of wind.

Ottawan: I would rather consider the practically of such an action since they have to change the hanged male flowers every few days in order to have consistent results. A grafted branch might have to many or not enought flowers to have consistent results.

I was also advised that a single male flower can have between 300 to 400 wasps. However, I am not sure how many wasps are required for a single female flower.

What is also interesting is that some people in Turkey make fig jam out of the male fruits. However, they have to pick the male flowers before the wasps enter the flowers.
treesofjoy.com has a link to a Turkish web site on how to make jam out of green figs. I would probably guess that the receip is similar.

Here is a link that might be useful: Google translate of Turkish green fig jam