I see that you're leaning more towards the rebel and you make some good points about it but is there any way to lower the height for the DRs or DRZs? I've noticed that one of the main points used against the dual sports are that they sit too high for someone of my height.
You can lower either bike but not to the point of ideal for you. But maybe an off road bike might be a good choice also (strictly off road).
Okay I am going to forget the aspect of building a cafe bike and stick strictly to learning to ride because that is most important for your safety.
I know a lot of folks don't care for the rebel as a good choice for learning and I know it has its limitations.........and I know they are other choices out there that are good choices as well however......I am still going to toot the horn for the rebel because it is best suited to your height and riding experience (none). If you were my son I would feel better with the rebel.....not a DRZ400 with a 35 inch seat height, not a 450 lb 750, not a GSXR600, etc.
Another aspect to learning is intimidation. Nothing is more unsafe and intimidating than a bike you don't feel comfortable with.
Also your familiar with Imperial Highway right? When I was young my first street bike was a 1981 CM400E. Keep in mind I had many years off road so I was not new to motorcycles just street bikes. We lived in Yorba Linda and my dad insisted I ride all the way down Imperial Highway and back at least once a week. Not a lot of turns but enough, with some higher speed areas and a lot of traffic. This stop and go, turn, speed up, etc taught me the importance of city riding. The next year I bought a brand new GS1100ES.
Good luck and happy riding