I found a great new local bread but it has a few things I can't have.  So what could I substitute if I made my own?  Below are the ingredients and the ingredients marked in red are what I need to find a substitute for.  Plus I have no idea of course how much of each of all the ingredients I'd need to actually make the bread.  Thanks for suggestions and any "bread maker knowledge" out there!

Organic Teff Flour
Organic White Rice Flour
Organic Corn Starch
Organic Brown Rice Flour
Cage-Free Eggs
Organic Extra Virgin Olive Oil
Organic Sesame Seeds
Organic Coconut Palm Sugar
Sea Salt
Xantham Gum
Yeast

Quoted from BluesSinger

I found a great new local bread but it has a few things I can't have.  So what could I substitute if I made my own?  Below are the ingredients and the ingredients marked in red are what I need to find a substitute for.  Plus I have no idea of course how much of each of all the ingredients I'd need to actually make the bread.  Thanks for suggestions and any "bread maker knowledge" out there!

Organic Teff Flour
Organic White Rice Flour
Organic Corn Starch
Organic Brown Rice Flour
Cage-Free Eggs
Organic Extra Virgin Olive Oil
Organic Sesame Seeds
Organic Coconut Palm Sugar
Sea Salt
Xantham Gum
Yeast

White rice flour could be replaced by more brown rice flour.
Corn starch by arrowroot.
Coconut Palm sugar by any compliant sugar - although you may have to adjust the amount or liquid level depending on whether your sweetener is liquid or powder, etc.

Why do you think they used the Brown Rice flour?  to make the bread lighter?    Will Arrowroot have the same effect as cornstarch?  

sorry to ask.. I don't know much about this stuff!!

for the sweetener i could use date sugar or dried agave...

Quoted from BluesSinger

Why do you think they used the Brown Rice flour?  to make the bread lighter?    Will Arrowroot have the same effect as cornstarch?  

sorry to ask.. I don't know much about this stuff!!

for the sweetener i could use date sugar or dried agave...

I don't know why they used what they used...  One thing I do know is that they didn't just guess at a recipe or make it once, they tested the recipe enough times to get a product that met enough parameters to be able to sell it.  To do this, they had to have reasons for what they did.  My guess is that the white rice flour helped it "stick" together better.  You might use some flax meal to do this as well...

Arrowroot has many of the properties/reactions of cornstarch, but not all.  For bread, I expect it will react very similarly, without the lectin reaction when you eat it...

Your sugar subs sound reasonable - although you may have to adjust the amount due to desired sweetness, but usually after you make it once or twice to judge variability, etc...

I can't say for sure how to make this bread, but I use only a little bit of teff, compared to rice flour--maybe 1/4 cup teff: 2 cups brown rice flour. I like to include a bit of tapioca or millet.  
I sometimes skip the xanthan gum, which is for texture, as it is an avoid for me.  The tapioca seems to help the texture, although it is merely a starch with no real food value. Arrowroot is also good for this.

I haven't had a chance to search for a recipe, but I'd recommend trying to find one. Gluten free bread doughs are very wet, with more eggs than required for gluten doughs.

I wish you luck! I was a competent gluten bread baker and have spent the past 2 years trying to figure out the chemistry of gluten free bread.
If you can tolerate einkorn flour, it creates a wonderful bread. Einkorn is an ancient for of wheat, which has not been rated by Dr.D.