LDMOS device properties and applications

Hi,

I want to know more about LDMOS

-How is it different from normal MOS?
-What are the Advantages?
-What are the disadvantages?
-Compared to normal MOS, what are the Ron and Coff, and Ft?
-In what applications is it used?

-I hear it is being used much in base stations PAs, but in different technologies than CMOS, is this right?
-I also need to know, if it is a high power device, then why isn't it used in RF switch applications, like TR switches?

Thanks in advance