Wow that's a lot of questions! I've got the answers to some of them, so here goes:
In the Listening test there can be several versions of accepted answers, so "6am-10pm" or "6am to 10pm" will be equally correct (just keep the am/pm). The same goes for Y/N or Yes/No and T/F or True/False.
If you need to list 3 words in your answer, separate them with commas.
Articles "a" and "the" - if you're completing a sentence (filling in the gaps or the like) it needs to be grammatically correct and if that requires an article - yes, use it otherwise you'll loose marks.
Not too sure about the capital letters - if you can copy the way it's in the text - do it.