Virginia, please don't be so upset - we are trying to help you out!
The pattern doesn't tell you what size needle to use because it is not written for one particular yarn. You can use any yarn that you choose and the first thing you do is make a gauge swatch with that yarn using a needle size that would be appropriate. Why is it you don't want to make mittens on a size 8 needle? If you want to use a bigger or a smaller needle size, use your yarn and whatever needle you choose and make your swatch. That is the first thing you need to do before you can make any
calculations, metric or imperial.
Now, I don't understand why you can't just input your measurements, in inches, into the formulas
. Your measurements are really just 'units' it doesn't really matter whether it is inches or cms or what have you. If you are making your measurements in inches, and you are measuring your gauge swatch in stitches per inch, there is nothing to convert except for the two places in the written part of the pattern where it says 5cm in one spot and 1cm in the other spot.
So, for example, your hand circumference is 9", which is 22.86cm. If you use the gauge that they have as an example in the pattern, which is 21 stitches over 10cm (21sts over 4"). 21sts over 10cm means that in 1cm you have 2.1sts. In inches, you have 5.25sts per 1". If you multiply your hand circumference in inches by the gauge in inches, so 9"x5.25" you get 47.25 stitches to cast on. Rounding up to the nearest even number as the pattern tell you to brings you to 48 stitches. Now, if we do the same thing with the centimeter measurements, you take 2.1sts(per cm)x22.86cm(hand circumference) you get 48.006 to cast on. So in both cases you end up casting on 48 stitches.
Does this help???? I tried the same calculations with your other hand measurements and it all works out, so all you need to do is plug your measurements into the formula, once you have your gauge swatch made, and go from there. It's not as complicated as it sounds!
As far as what type of needle, you will not be using a circular needle because you are making mittens, circular needles are not small enough. The only way you would use a circular (or two) is if you were using magic loop knitting or knitting in the round with 2 circular needles. Otherwise, you will be using dpns.