some rambling thoughts about fabric choice:
people make garb out of trigger/poplin, cotton bottomweight, various synthetic fabrics, linen, wool, brocade, silk and probably many other things.
if you are interested in wool or other natural fabrics heres a great explanation of the basic important info:
viewtopic.php?f=5&t=30969when i'm in the fabric store and i dont have something specific in mind already i look around through the thicker fabrics and look for something that looks durable, is cheap, and is in the color i want.
when i go for trim i go over to the quilting section, they have all the fancy colors over there, and try to find the closest match to the color i want.
also, try to find bias tape, and see if they have it in any of the colors you want because its a huge time saver when it comes to hems, neck holes, and stuff like that.
when you see fabric you like check the tag on the bolt to check out what it is made from, i generally steer clear of something with polyester in it when it comes to a tunic, but when it comes to pants i dont mind so much.
you'd probably do well to use a heavier fabric (trigger, bottomweight, etc) for your hakama and a lighter fabric (linen, worsted wool, some kind of thinner cotton fabric, etc) for your tunic, that way your pants are durable enough for ground fighting and will last you a while, and the tunic will be light and breathe so you can keep cool on the field.
hope any of this helps