Q1 Is there a programme, with which one can apply other ring tones for different groups within the contacts?

A1 No

Q2 How do I show the name of the company in contacts?

A2 Tap contacts > view > By company

Q3 Can I add any new fields in contacts? Can I change the field name of the existing field given in the Xda II?

A3 No. The default field names cannot be changed.

Q4 As contacts are saved to the phone - if a second sim card with the same contact number as the previously installed sim card, will it over write the old contact or add the same contact twice?

A4 It will write over the old contact and not duplicate another.

Q5 How do I save a contact with multiple phone numbers to the SIM?

A5 Contacts with multiple phone numbers will be saved as individual addresses on the SIM.

Q6 How do I dial a phone number stored in the SIM?

A6 Go to the SIM Manager under Programs, tap and hold the stylus at the contact you wish to call, wait for the menu to pop up and then press the call button.