Yes. Even if the primary way your students watch your flipped videos is in the classroom at the beginning or during the lesson, you have created a resource they can access as many times as required to learn the information and/or skills. Also, you may be surprised that some students start accessing the videos outside of class, especially if they are available on platforms such as YouTube (where they can be easily cast onto smart TVs).
It depends. You have to balance the time it will take to create the video with the payoff for your students and their learning. The best approach is to make your videos as quickly and as efficiently as possible using tools that you're already familiar with. Avoid spending large amounts of time on 'bells and whistles' and make sure your video is more about WHAT you're trying to teach instead of focusing on the appearance of the final product.
It shouldn't. In fact, it should have the opposite effect, as instead of being up the front (or a 'sage on the stage') you'll have a lot more time to spend helping students individually while they're working. Having this additional time to work with students more closely should actually help you to get to know your students and how they learn even better.
If you're already familiar with PowerPoint, this can be a really easy place to start! However, if the idea of using PowerPoint is a bit intimidating, look at using the free version of Screencast-o-Matic; this is a simple, easy to use tool where you can simply capture whatever is on your screen (and a video of yourself too if you like). Your video will only take as long to make as it takes for you to record it (plus a few extra minutes to export it once you're done). Once you feel confident with simple tools, it can be good idea to look at expanding your repertoire of video creation software and webware.
Research into flipped classroom pedagogy is really only in it's infancy, and many educational theorists are not yet sure of the efficacy of this approach when compared to a more traditional teaching method. However, there is some research to support flipped pedagogy, and it is likely in the years to come we will be able to gain long-term data as to it's impact on student learning. To read some of the research so far, click on the links below: