Logic management (ie:which map to load) before engine starts

i am very new to Unreal Engine and i am trying to understand hot to get things working.
I need Unreal engine to create a simulator (not really a game). I see that every tutorial focuses on using editor. It looks strage to me, because what i expect is to write code to control my application.
For example i would need to decide at runtime which map to load and which objects to place on map (maybe defined in a xml descriptor).
No tutorial could help me in understanding the correct flow to write a standalone application/game.
Can someone explain me how to manage a correct startup chain (setup variables, load information from xml descriptor, load a particular map, populate the map with object and so on…)?
Thank you very much for your help.

You can first load up a dummy map, and then do all this in c++.

Thank you for your reply. What i would really like to know is the real flow in developing a complete solution. From official documentation i can’t see a real tutorial on creating a complete standalone project. Do you think such information is available online or do i have to buy some book or something else?

It is available. In teh documentation.
Remember that you can use fake levels for everyhitng.
The main menu is jsut an empty level with the menu displayed. Loading screens are often a level too. So, basicly:

  1. The game starts and you load the menu level.
  2. You open the game via the menu, and start another level.
  3. You play.
    Remember that there is the class Game Instance where you can hold variables for the whole duration of your app.