Called Kindle customer service using Skype. After being transferred several times, they finally suggested changing the country from the US to Austria. The strange thing is that two titles I ordered after arriving in Austria had downloaded OK. The others remained pending. Amazon CS told me that Amazon allowed a couple of downloads but then required I change the country. Well, changing the country to Austria didn't work.
Before calling CS again, my son turned on Airport (WiFi) on his Mac. After many changes and attempts, it turned out the Mac protocol is different and the Kindle can't connect through Airport! Ever the techonogeek, he tried connecting wirelessly through his iPhone. Bingo! The download was slow (3G and in a small village between tall ridges) but it worked!!
Bottom line is that downloading content via USB didn't work and Amazon was no help. Apparently, content bought through the Amazon site sits there pending until there is a WiFi connection. Also reinforced that where there is the will there is a way.
Thanks to all for your assistance.