Welcome! Dev-section is more to development disucssuion, better choice would be LibbeCAD-user.
But to your questions, LibreCAD is not a free version of AutoCAD(r), but is very decent 2d-cad that stands on its' own . So I think better option would be starting with tutorials and docs, links are at the top of the main page.
Green icons have been disucssed before. I like them, it's about taste. For now get used or think some other option, LibreCAD is open-source, and as most of them there just are not enough contributors. So icon colors are not at the top of the todo-list.