First, I'd recommend that you read this thread (assuming you haven't):
great Kilt

Another resource that discusses size and construction can be found here: Early Kilt

Your subject matter experts on this forum off the top of my head are: M.A.C. Newsome, Woodsheal, and Sir William...and there's probably about 10-15 others that have greatkilts as well that I haven't immediately thought of.

Regarding your question about measurements and how much tartan, etc...

Meters vs. yards: The meters vs. yards question is nothing to get wrapped around the axle about. A meter is roughly 39", which means it's about a finger's length longer than a yard...so you can use yards and meters virtually interchangeably...you just get a little more tartan for your money (ie. if you ordered 4 meters of fabric, you'd end up with 4 yards + 1 foot).

Tartan Width: The "norm" these days is for tartan to be woven in double width, which is usually between 54" and 60" wide, depending on the mill (most common is 54" and 58" IIRC). Some mills still weave tartans in single width which will normally be 27-28" wide. You just need to be sure of what you are ordering when you order.

How much tartan do you need?: Original great kilts (as explained) by Matt Newsome in the Albanach.org article) were made out of single width tartan of about 25" wide. At that width, a piece of tartan of approximately 8-9 yards wide was required...the tartan would be cut in half and the two 4-4.5 yard pieces were then joined together to make a rectangle of tartan about 50" wide (two widths) by 4 yards long. Some have stated that they have found 3-3.5 yards to be enough length. If you are larger in size, you'll probably need at least 4-5 yards. If you want to be authentic, then you can look specifically for single width tartan or rip your double width fabric and then rejoin it by sewing to create that seam look. If you're buying double width fabric and don't care about the seam...you can just leave it as is. A piece of tartan between 3.5 -4.5 yards will suffice for most people.

Hope that helps...I'm sure others can share their experiences and advice. I've never worn one, so all that I've said her is just summarized from what I've read and been told.