Much of what a court is going to look at is what's happened in the three years. If you've continued to have contact with your ex on a regular basis, and there have been further "issues" between you, then there's a chance that a court will extend the restraining order again. If, as much as is physically possible, you've gone out of your way to have NO contact with her, then your chances are much better.
This is a good question. I have dealt with many cases with similar questions in the past. There are several specific code sections that deal with this issue. I can give you some general guidelines but I would want to see the petition before I gave more specific information for you.
First, this is not a renewal. It is clear under the code that a petition for renewal of an RO must be filed before the RO has expired. This is a new, and separate case that must be determined upon it's own merits.
Did the court issue the temporary domestic violence restraining order in this new case? If no your chances of prevailing at the time of the hearing are much better. But it is a fact driven question. If you are able to retain good counsel I would do it.
The date of the restraining order is not what most judges will look at to determine if a new RO should be issued. It is more a question of the most recent incidents of abuse and what has occurred since the issuance of the original RO. The court will also look at the basis of the original RO.
So far as defenses it would be good to review the petition to determine which defenses to which claims you should assert. If I can be of further assistance to you, please do not hesitate to contact me.