Integral attachments (scopes, shoulder stocks, reflex sights) arent default attachments to set integral attachments you have to add several parameters on your own but than you will run into problem. Maybe there is a smoother way to do that? Many weapons have integral folding stocks. The system should know if the weapon uses an integral stock or not! Surely both version integral/mounted stock will get an option to un-/fold same for other integral/mounted examples. Integral stocks could get certain parameter based on the mounted variants.

For quite some time: Attchment Icons.

For the "button-thing" if pushing the button you switch to the gerneral weapon page where can choose several action like un-/folded stock which magnification factor ectera all are listed under the primary stats of the weapon. Fe. next to the scope icon i would suggest to add two buttons (very small ones), "+" and "-" higher/lower the magnification in high of 0.5%.

And one question i'm not an expert but as far as i know several scopes are static. Maybe an option to choose if the scope is fixed or not?!