My PhD was in mathematics with applications to medical imaging. My presentation was done in LaTeX and the basic structure of the talk was
1) Introduce the broad field. Then for 4 particular topics:
2) Introduce a particular subject and why it's worth looking at
3) What are the issues and why do they matter
4) What others have done about it
5) What I've done about it and why it's better

I expected mine to be 25-30 minutes of presenting followed by a discussion about the thesis. In fact, the panel asked almost all of their thesis-questions during the presentation, which ultimately took 2 hours, followed by some brief questions and passing without corrections :). It could be different in your field, but in my mine, some important things were highlighting the importance of the research area, talking about what others had done, and very importantly, emphasizing the novelty and significance of my research. A friend told me that, in his VIVA, he finished his talk and sat down at the table, only for the external to ask, "So, what's actually new in this thesis?"

I did my PhD in mathematics and, despite having passed the VIVA 2 months ago, my supervisor has never read the thesis. He went through the contents page and the introductions to the chapters but that was it. A colleague in the group sent the same supervisor her chapters one by one and didn't get much of a response. If the supervisor is confident enough to let you write the thesis, I think that they assume that you'll write it well and I'm sure you will. If you've made the odd grammar mistake, that's not a reason to fail. Your panel will just give minor corrections. I've read the theses and papers of 3 people who weren't native speakers and most of the corrections I gave were about sounding more English but the original sentences still made sense so it didn't really matter.

Similar story here. I left a good job in industry to take a PhD and now feel less employable than I was before. 5 months since I submitted, 2 since the VIVA and still looking. Despite several papers, teaching experience and conference talks, I've received the same string of rejections, including being sent the rejection e-mail by York for a particular postdoc THREE times! I also got the impression in one interview that my experience in industry counted against me. It does help to use this time to assess what difficulties you're having RE getting a postdoc. In my field, most postdoc positions seem to require a computer scientist rather than a mathematician. I felt that my C++ skills weren't strong so I've been writing my Matlab codes in C++. More publications always help and my supervisor has at least allowed me to continue using the research group's facilities, so I'm working on a lot of projects. It also helps to top up the funds! I haven't taken a part-time job because... I could land a proper job any minute. So I seem to be working most of the time without actually being paid a penny, which is depressing in itself. As a result, my money is almost gone and I've applied for a university job as a "research associate," which doesn't require a PhD but is at least related to my field, simply because I need the money and it'll allow me to have a research position. I'd say that if you're going to hold out for a postdoc, keep in mind that it could take some time and take cr*p jobs while you wait it out without worrying about p*ssing people around by leaving 2 weeks later. I think it's also a good idea to set a timescale - I've decided that if I don't have an assoc. prof. position by the time I'm 35, I'll give up while I'm young enough to retrain.