1) It would be nice if there where the availability to define custom properties on each block we add in the model (by example, a simple user defined text value)

2) when we export to obj, it would also be nice to have the option to remove the hidden faces (by example if there is 2 cubes aside each other, there is 2 faces that are not visible

1. Could you explain what you mean by this? What would the custom properties do or how they would behave?

2. This is not possible, while in your example it'd be relatively easy to detect which should be removed in a lot of edge cases it'd be impossible to do so. If the feature would be added, it'd have to work all the time - not half. So that's why I'm not planning on implementing such a thing currently.