I would suggest that first of all you divide your questions above in two groups: the ones about society and the ones about...well, the rest.
You can start with either group of questions. Say you start with society: try to answer those questions before you write. Ideally, give them short, summarised answers and, if necessary, add one or two readings for deepening your knowledge on the subject.
If possible, talk to someone (one or two friends with open minds, no more) and let them ask questions that might help you find loopholes and inconsistencies in this society. Make sure you feel satisfied with the general picture of the society. If necessary, ask questions on the World Building SE; you'll get lots of nice feedback. Do not take more than a month on this set of questions.
Try to answer the other set with your current knowledge. Again, make the answers short and add one or two reading if necessary. After that, go back and mark the answers which you aren't sure about. Then go back and mark the questions that are essential to the plot.
Say that you have a question about new ways of transport. Would it affect the plot if that new transport had to be nixed? No. This means that researching this particular point is not essential and you can start writing before you research it. You can easily replace a car with a bike, it just makes the trip a bit longer.
Now say the question is how memes work. This can potentially affect the plot. Imagine you write a whole chapter about how the farmer is having his work messed up and then you realise the science you used was faulty. It isn't an easy fix. You can't just replace A with B. So that question needs researching before you start writing.
Research just enough to create the rules of how the "physics" of your world work. If it makes you feel comfortable, mark the ones you know are scientifically accurate and the ones that you made up (and maybe the ones that are half way). Then tell yourself, as @FlyingPiMonster says, the important thing is that the whole is consistent. So look at those rules and make sure they are consistent.
Keep in mind that you can write and research at the same time. So, research enough to create a solid scientific (not necessarily accurate, and seldom to a fault) frame before you write; then start writing and do a little research on the side as necessary.
While doing research is very important that you keep the story in mind. A fascinating topic can catch your attention and make you lose yourself investigating it. But does the story really need you to research it that deeply? Really? Keep a sketch (in diagram, timeline, or as it works for you) by your side as you research. Tick the points you feel confident you've got all the answers and rules straight. Do not investigate those points further.
Once you've researched enough to answer a question confidently, stop investigating. You can always say "well this is fascinating and I want to read more about it" and it's fine. You can start writing and at the same time keep on reading for your personal satisfaction and completely apart from the story.