Hi First Son,
Most of the TDH members will tell you to use 100% cotton twill or brushed twill. The color is a topic of debate for everyone. If you are concerned with being exactly accurate, you may want to buy a reference CD. You can purchase one here.
There is a thread started by Loanstar that is very helpful. Loanstar makes Jango flightsuit and if you read the thread from start to finish, it explains every detail and also discusses color. After I type this I will find the thread and post it.
For a pattern I use a KwikSew coverall pattern, #3389. This pattern is design to wear over street clothes, so when your mother cuts it out she will want to cut at one size smaller than your measurements. If you look at the pattern and measure a size Medium, the cut the pattern at the small line.
This would apply to all of the pattern, except for the torso length. You should probably keep the torso length the same.
I will search for a couple of links and post them here to get started.
You can use the search function and find the answer to almost any question you would have.
Feel free to PM me if you have any questions.
Debbi