For cargo aircraft or air freighters, the An-12 *is* considered ‘light’ these days. It’s a bit smaller than a C-130 as I recall.
The An-12 normally has a cockpit crew of 5 just to fly - two pilots, a flight engineer, a navigator, and a radio operator. Add in a significant load and you’ll want a loadmaster and an assistant or two.
Refueling in Jordan does make sense as the plane at max payload only has about a 2200 mile range. Serbia to Jordan is about 1300 miles, then they’d have to fly over/around some countries you really don’t want to land in. Like Iran. Assuming they wanted to avoid everything that’s likely to flip a missile at them or confiscate their airplane in the name of the Revolution, a stop in Jordan to refuel makes sense, followed by a stop in Dubai, another one in Mumbai and then they can make it to Bangladesh from there and still have fuel in reserve. You want to have a fuel reserve at all times as when the airplane runs out of fuel, you can’t just park it by the side of the road and walk to get a jerrycan full of fuel to get you going again...
Serbia has a significant arms industry. For starters, they have Zastava Arms, part of the large diverse Zastava conglomerate. Anything the former Yugoslavia could make, Serbia can make.
Replies like Spkytr’s are why I subscribe to Free Republic. I don’t think you’d find this level of democratized open source expertise anywhere else on the Internet.