Hi Bookworm. In my experience I can tell you that you need to do a lot of reading before you are be able to ask the right questions in your research. At least that's what I did. My reaserch proposal was probably very generic at the beginning.
I have often been told to focus on something very specific from the start. I suppose it depends on the field you are in. I found out quite the opposite. If you don't have the bigger picture you have a very partial view of things. You also need to know what resources you have available and how you are going to use them. Ultimately, it's up to you to decide questions, methodology and timetable and all these evolve with time and knowledge. Probably the final result will be very different from the points you have started with.