When I used to brew extract I used 100% wheat extract. As zimaclone pointed out most wheat extracts are 50% or 60% wheat. If you want 50% blend (which is what I do all grain, 50% wheat, 50% pilsner) then go with all wheat extract.
I have never used honey malt in a hef before but when I put 4oz in my Saison it was fairly apparent. I think 4 oz is a good starting point, go up or down next time you brew it depending on what kind flavor you want. The honey will pretty much ferment out and help to dry out the beer some, don't think you will get much if any honey character with it. It will help the beer from getting to sweet.
Don't know if you need the second hop addition. I usually just use bittering since hefs don't really have any hop flavor. Just a personal thing.
Last, adding orange to the beer will not make it a wit beer. Hef vs wit may have similar grain bills but are generally yeast depended for flavor (for the most part). If you are using a hef yeast you are making a hef. Hef yeast and wit yeast have very different flavors, it has nothing to do with orange.