1. If you had given a Notice in Newspaper for Name change than please enclose the copy of advertisement .
2. Yes you can apply for passport with New Name after fulfilling requirement of above point.
3. You need to verify yourself by two character certificate through two different gazzated officer who ensure that your name changed & they know you.
4. Yes, you may need to submit the notarised copy of affidavit at the time of submitting necessary documents.
5. You need to fill your formal name in the form if given, likewise in PAN card Application they have a coloumn that whether you have been known by any other name or not.
If you are not satisfied, Ask again.......... ?