1. Depends on the journal, the average is around 2-6 months. Good journals usually give you a quick response whether or not your paper will be forwarded for review. Remember not to submit the same paper for review at different journals - they cross check with each other, and it can result in all of them rejecting your work.
2. This is subjective, as it depends on your work. Questions can range from the validity of your data to methodological choices you've made. Do not be discouraged by a bad review, instead use it to beef up your paper for future submissions.
3. You publish whenever you're a step ahead. Eg: Your project has 5 milestones, so you start publishing the results of the first milestone once you're already working on the second. It helps ensure that other researchers can't overtake you. Constant publication keeps you on your feet, especially when it comes to keeping up with current literature. Last but not least, try stay away from review papers. I see a lot of first first year postgrads publishing these based on their literature review - review papers are generally published by experts who have years in the field; any journal that willingly accepts a review paper from a freshie isn't a good journal to begin with.