Is there a way to order the furniture on the 2D image so that items like umbrellas appear above and chairs show (partially) under a table?

Ramsheed,

You can't draw glass walls in SH3D.

The workaround is as follows:
1 - insert a door frame or a service hatch in your wall and give it the correct dimensions
2 - download one of the glass boxes in the Attachments section
3 - import the glass box
4 - resize and insert the glass box in ...