Cougar, you're describing a typical GUI parametric CAD software. Fusion 360, Solidworks, Designspark Mechanical and Solvespace all do this. The drag and drop, stretch and so on is the G (graphical) part of the GUI. Typing in dimensions is called dimensioning, and yes solvespace can do this, select a line or circle or whatever and press D on your keyboard or click the dimension button in the interface and then edit the dimension line that pops up.

There is a youtube tutorial series on solvespace, might be worth checking out. I personally prefer to learn by doing and find it more effective.

OpenSCAD is scripting, rather than command line which is much less daunting. And it has a pretty good debug and error check tool, when something goes wrong it usually tells you exactly where and gives you a hint as to what might have gone wrong. I personally found the scripting language fairly intuitive and easy to pick up, but it isn't my first dive into programming. Most of the commands are sensibly named, cube() makes a cube, sphere() makes a sphere, translate() and rotate() do what you'd think etc. It's definitely not for everyone, though.