Not all the Nazgūl were caged in Minas Morgul. Khamul, the Second of the Nazgul, for example, was most of the time in Dol Guldur, even after Sauron departed there. Many I guess were always on their paths due East and South to tell the people of Khand and Harad that Sauron was Lord of All and all that crap.
You seem to point out that Sauron didn't use them until FotR. I don't think so. He made use of them as best as he could, be it wasn't known to the White Council for he kept it a great secret, knowing them to be his strongest servants and that their attack would be even greater when done so in surprise. Sauron was always in search of the Ring, looking from Barad-dur. I guess therefore that he explained his plans to the Nazgul and left the gaining of an army and governing of that army to them.
I don't think the Nazgul saw Minas Morgul as 'home', but just as the place Sauron said them to bread an army in. The same with Dol Guldur.
I guess Sauron could talk telepathically to them, but not over such great distances. The Palantir is a good. I guess that was one of the greatest instruments he had in his possession. Because of it he could see many things:
- the governing of his Army
- the governing of the Army of Gondor
and with these things he discovered the other places where the Palantiri are, and could do very great damage:
- corruption of Saruman
- the craze of Denethor
He may have used the Palantir also to transmit messages to his chief Servants. Yet about the Palantiri I'm not so sure what their abilities were. I should read the UT again.
greetings,
lathspell
P.S.: Kalimac,
Nice! [img]smilies/wink.gif[/img]