My very first steps in designing

Let me start by saying I haven't been very good at my NY resolutions. I said I'd be kind, but the other day, there was a little old lady driving at about 35 mph on the freeway (the one where you can go 60mph, which really means you can go up to 70mph!!!). I passed her and then gave her the evil eye. And then I thought about how I wished I'd had signs in my car to flash at people. Oh, I am bad, aren't I? Well, my signs would say stuff like this:
* Hey buddy, use your signal! I can't read your friggin mind.
* Pay attention to the road, slacker. My lane is not your lane!
* Hey, thanks for letting me merge. NOT.
* GET out of the road, slowpokes.
* Go at least the speed limit!
Funny, funny thing about how I have road rage on the freeway - I didn't drive on the freeway until I was 30. Sure, just a handful of times before that. And now look at me - I am Queen of the road! ;)
Hehehehehe.
Well, now, I must carry on with my designing process. Now, going forward, I am going to assume a few things and if that aggravates the heck out of you and you don't know what something is or you want me to explain, please leave a comment and I'll reply. Otherwise, it's probably simple and you think I am crazy for sharing what I think is some little secret into the designing process.
First and foremost, you are going to need one of these:

When I first started knitting, my knitting guru said, "you need to swatch to check your gauge." And I replied, "blah, blah, blah, whatever." I thought it was a waste of time. And, honestly, sometimes it is. But if you are making clothes, it's a must!
I am going to be making my daughter a skirt. To tell the truth, I have never made a skirt. So, this is a learning process for us all ;) But, I'm using what I've learned with other projects and applying it to this one.
So...back again to the swatch.
I used my new Rowan Wool DK with size 7 needles (oh, Kristy, I invested in size 7 needles ;)) I like my yarn a little loose, with movement. The yarn calls for 6 needles, but I'll use 7. I cast on 20 and knit about 4 inches to create somewhat close to a 4x4 square.
(Here is a little trick from me to you: don't bind off. I leave my sts on the needles so I can rip it apart and reuse the yarn.)
Now, always count the stitches at least twice. First, stitch wise and then row wise.

Using my Rowan Wool DK and size 7 needles, I have 5 stitches per inch, or 20 stitches per 4 inches. When I go to make calculations, this will be useful information.
Then, I count row-wise:

I have 6 stitches per inch, or 24 rows per 4 inches.
Next, I calculate the measurements of my model. Here she is:

But I decided to just use a skirt that she liked for measurements.

Here is the breakdown of the information I gathered:
1. waist = 22 inches, un-stretched
2. length = 28 16 inches
3. high thigh = 28 inches
4. low thigh = 32 inches
5. bottom = 36 inches, un-stretched
I think I'll knit bottom to top, because I like knitting things where I have to decrease as opposed to increase. Right? Don't even call me silly! So, the question is....drum roll.....how many stitches do I need to cast on?
Well, we know we can knit 5 stitches to an inch. And we need the skirt to be at least 36 inches across. I am going to go out on a limb here and say I'd like to add an additional 2 inches to the bottom for twirl, so we need at least 38 inches. 38 times 5. See, 5 = 1 inch. So, we need to cast on 190 stitches.
(((When I say we, I mean you and me. If you want to join me...)))