Regular pop rivets will work, a normal pop rivet gun is needed, and can be bought at a local big box hardware store.
As for the names.
You have an Airstream, The Land Yacht desigation was a marketing idea, they are all land yachts until the late 70's
International is a trim level. This was an upgrade package that changed from year to year.
Ambassador tells us more than everything else. All ambassabors are 29 ft long. The floorplan was the same for all of the ones I have seen. Rear bath mid twins and kitchen on the curb side and a large front lounge.
WBCCI #5501 AIR # 49
1978 Argosy 28 foot Motorhome
Wise men talk because they have something to say; fools, because they have to say something. -- Plato