Well...I did some maps on CODRadiant and GTKRadiant at past.
Probably I know the answer (nothing was changed after many years), but lets go...

a) It is possible like in CODRadiant put decals textures aligned and created dirty, explosion, etc... effects (in past I edit the textures on Photoshop, but decals on editor is an amazing feature).
screenshot-699.png

b) Prefabs in MohRadiant is terrible, because not is a model/object but a collection of brushes...ok, I know...is a map inside a map, but like in CODRadiant where the prefab is a object (you select the entire entity and not parts of them) is possible change the way of select prefabs for a single object (as we do with models ) ?



c) after 15 years.... I cannot remember how I did the curved roofs (using edge mode) , I got the result using vertices but I remember in past I did it using only vertices
screenshot-698.png