sandeep, J2ME is a set of tools and APIs to develop applications for various devices (like cell phones, PDAs, pagers) other than PCs. so, the APIs, and the implementations of the the JVM will be quite different from those you come across in JDK. no, there won't be any questions whatsoever from J2ME in SCJP examination. cos for the simple reason that its not there in the syllabus. so, just relax and go ahead with your preparation.
Depends what you mean by "J2ME". The Connected Device Configuration requires full support for the language and the VM bytecodes. The Connected Limited Device Configuration removes all floating point support, finalization, and a few other differences. In general, though, the use of the language is unchanged.