I can help you on question (4).
As long as the courses you are interested in are related to each other, that's fine. For example, if you wish to apply to MSc Accounting & Finance and MSc Finance you can explain in your PS why you are interested in Finance in general, and why both courses will help you achieve your goal. I wrote 1 PS for my application to both Fin Maths and Risk and Stochastics at LSE. The names sound different, but the contents were similar to each other, and eventually I even manage to get an offer at LSE. Hope that helps!