Hope to start a grain trucking business and just looking for some help.

Ok i am currently going to college for business degree and i want to start my own grain trucking business back on the farm afterwards. I am taking a small business management class where we have to make up a business plan.

It is not like a professional plan because people, not in business degree field, are taking the class too. The teacher does want some actual good figures, he doesnt want us just to make some up. So i just need some figures to base my starting expenses and income. I have only been hired by other farmers to truck for them and so im not sure what the figures are when you have your own truck.

1. I was wondering about how much do grain haulers charge per bushel and does the price increase the more miles they go? Is there a flat rate that people charge for loads that are maybe a half load for the semi, to still make some profit? (Is there other ways truckers charge to besides per bushel or is there other ways they do it)

2. Does anyone know what the average cost of repairs per year would be if i were to put on maybe 70,000 miles or around that?
What do most shops charge for labor?

3. Last what is an average owners salary i should give myself out of the business in order for living costs and other personal expenses?

Mainly i have most of my expenses figured out except whats about and then i primarily want to be able to put a decent perjection on for my sales.

Thanks for any help and advice!