Hi..
Well.. i am doing a project in J2ME .
I heard that j2me midlets cannot run on some of the (latest) mobile phones and there involves a hectic work to deploy them in mobile. Is that so? .
How to deploy my j2me midlet in mobile phone. ?
Copying the jar file (or jad file) into the mobile is only thing that i should do inorder to deploy my app?
My project is basically a banking application.
what are the minimum mobile requirements that i should have inorder to make my project work
successfully?

You wouldn't get them running on iPhone for sure, as Sun had long talks with Apple hopping to get JVM on iPhone but that was dismissed.
Android seems to have some tools/libraries to run it, but would you want to "poison" great user experience with almost 10 years old ugly graphics and usability issues?
Nokia Qt phones as before with original Symbian, you need to check models for specifications and see if able to run midlet (some do, others not)

Deploy JAR, JAD is normally used just as checkout from website to see if device is able to run midlet. In case if device can run it, then JAR is downloaded (comes from "old times" when internet connection was expensive and it was cheaper to download 10kB JAD instead of 5-10MB JAR)

As for requirements, aim for MIDP 2.0 any lower would be pointless as as I believe there is very low number of old phones.