Concepts about programming in Unity (Video Games)?

Hi, first of all, I’m new to Unity. I’m a developer from Argentina, totally new in programming in C# (The lenguage I want to use). I want to start making Video Games. I have a project idea but I lack the knowledge of some pretty basic concepts about Unity, so I’m gonna be asking them here, let me start:

1) How to handle screen resolution?
In HTML5 you can use CSS3 “Media Queries” for changing the elements position, or scalling them down. Also you can use “relative” values in position (Percentage values). How do you handle screen resolution in Unity?

2) How does scene works?
I want my game to have a menu, a profile selection screen, a main screen once you selected your profile, to upgrade some elements of the game, see your achievements, etc. I come to know that you need a scene for each one of this screens, is this that way?

3) How to save the player score and stuff?
How to handle gamesaving, profiles, achievements, scores, gemns, coins, points, levels and things like that? I want to save all this things in the computer of the user, not in a server, but how can I make this?

4) How to know the requirements to play my game?
How can I know what specs should a PC have to play my game? It’s not gonna be “The Witcher 3” or "Dragon Age Inquisition but I would like to know the requirements for my game.

Well, that’s all, thanks in advance!

1 with the new ui you have anchors and pivots that handle the resizing.

2 I would make a Scene for the Menu (switch between different Menu Panels) and for the game it self (this scene can maybe be split in multiple scene)

3 I save everything in serialized binary files. z.B Profiles: foreach profil a binary in a folder called “profiles”. How you create and save binaries http://tech.pro/tutorial/618/csharp-tutorial-serialize-objects-to-a-file

4 There are programms that limitate the power of your hardware (reduce ram, reduce ghz of processor, reduce mhz and vram of graka)

my advice for you is to watch the tutorials providet from the unity team Learn game development w/ Unity | Courses & tutorials in game design, VR, AR, & Real-time 3D | Unity Learn .
They will show you the golden path of unity.

I’d second the tutorial videos here on unity3d.com its a great intro to working with unity.