Well, I'm not any guru myself and thus I will give you only some simple recommendations. First of all, you said you have been mapping for two days, right? If you haven't used Radiant before that, I would certainly recommend reading all and everyone of these tutorials:
RichDiesal (this man knows everything there is to know)
Kayron James Mercieca (lots of nice and easy tutorials)
So, to put it simply, start with basic stuff, and if you want to spare yourself, make a little, indifferent map, where you will learn these things, then when you think you are ready, start making your explained mission. Scripting and all such stuff you can learn along the way. And you don't necessarily need any programming apart from ICARUS.
First make your map, then start worrying about cutscenes.