To aid assembling parts with CA as well as to avoid unintentionally bonding a model to something, I assemble the parts on the surface of an old stainless steel ruler. The CA bonds to the stainless just enough to help hold parts in alignment while they set, but it's easy enough to gently pop them off the ruler with the tip of a sharp knife.

I've read lots of advice, howto, intro, and helpful things on the internet about modeling railroads.

But nowhere is there any information for the beginner, [ ... ]

For the TL;DR - just scroll down an look at photos is useful since it's about architecture :) Feedback appreciated !

I want my layout to have a high level [ ... ]

Scratch building is defined in Wikipedia as “The process of building a scale model "from scratch", ie. from raw materials, rather than building it from [ ... ]