Hi there @Lollosk,
Welcome to the Forum! It’s great to see you here and great timing too! We’re currently working to bring Auto Layout to Sketch and our Product Team is requesting feedback! By the way, I agree 100% with all you mention here: more control, visual feedback, create our own solution.
Check this post and please feel free to say what’s a must, what you need and what you expect from this new feature! 
Call for feedback: “Auto Layout”
Now, regarding what you mentioned about visual feedback, Sketch has tools that can help with positioning and paddings. I ran into the same issue as you: how to set my paddings with precision and I use these two things in Sketch. This is what I use:
- Select a layer and press ⌥ (Option), this will show you the distance between your layer and other layers
- Use the alignment tools on the Inspector. For instance, to center a button label
I made this demo video, I hope it helps: