Greetings Dean:Welcome to the Forum.
Although they must cover the same task when giving a practical, every examiner is different. Also, because the task list is longer than a typical practical test period, the DPE is somewhat free to pick and choose what they want to see.
What to expect as far as time and will vary, but the flight portion will be somewhere about 1.5 to 2 hours. Your instructor will be the best person to ask about specifics, but all checkrides start with paperwork, payment, then a briefing of what to expect. Most DPE's will then go into the oral. How they conduct the oral varies, but you'll be asked questions and will have to explain your choices for your flightplan (some DPE's will have you put together a flight plan before the test and others will have you do it on the spot) and you'll then have to make a go/no-go decision based on all of the information available to you.
Being nervous about taking your practical is very common, so don't feel bad about that. Everyone is nervous to some extent even if they know the material cold. What I can pass along is remember that the whole point of the practical test is to see if can operate safely as pilot in command. The DPE should tell you (you should ask if they don't) that you'll be PIC during the checkride. You've done this before if you're ready for your checkride. Some find it less nerve racking if they view the DPE as a passenger and not an examiner.
If you're still very apprehensive about it, most DPE's will gladly meet with you before your checkride at no charge so you know they don't have fangs (wells most don't! ) etc.. Just let them know that you're nervous about the upcoming test, etc.. Like I said, it's very common, and DPE's will go out of their way to help. I've yet to meet a DPE that doesn't want you to earn your ticket. However, they won't just give it to you. You have to demonstrate you're up to the responsibility.
Hope this helps and good luck on your checkride.
Ben