I never make things for myself - I live in Bangkok where chill is NOT a problem - but I knit for others a lot. My suggestion is to start with a top-down raglan because this is a sweater you can try on for fit as you go. Once you get that down, you can move on to other types of sweaters, but really, a top-down raglan is easy, you can add design featurs such as lace and cables - BUT you can also try it on as you go, and if it is too big, take out a few inches and then decrease a bit. If you want waist shaping, shift to smaller needles (easiest) .... just so many options! Short sleeve, long sleeve, or just a cap - all up to you.
Standard cable, just with a long gap between the crossings.
looks to me like an 8-stitch cable, left over right, spaced out by: p1, k4, p1 (the k4 should look the same size as the k8 because of the narrowing that the cable brings - though it may be a k6 panel, the picture isn't detailed enough for me to see clearly to count.
The thing is also that it is fine, sports weight yarn.
I'm not sure what you mean by mirrored cables - but according to my understanding of your meaning, it would mean that on one cable you cross right over left and then to mirror that you cross left over right.
one suggestion from my end would be a blanket - i know it sounds large, but you can do one on big needles with several yarns all together and just use the knit stitch. Choose bright, funky colors and combine them in odd ways - get a big needle and just knit away, going back and forth! If you keep it by your chair and pick it up each time you sit down to watch TV or something, before you know it, it'll be done! (and the advantage of a blanket is that they don't grow out of it, which is a big problem when you knit clothing for a baby!)
Oh - about the flattering bit - I forgot to mention that when I made it I removed that shaping business - I didn't think the pattern really was helped by it. And I think it did make it more flattering on my niece (admittedly when she tried it on it was 90 degrees and she wasn't really interested in leaving it on for very long - she was here for Christmas!) to not have that shaping.
I would NOT rip out! 1-2 stitches really doesn't make much of a different in such a large project. Remember, one side laps over the other side, too, so I wouldn't think it would be a problem at all. If you need the exact count of stitches for the back, then just decrease an extra one; on the front, I don't think I'd bother.
May I suggest that you try doing something that isn't circular until you get used to how circulars handle? I have tossed my straights because the circulars are so much easier on my wrists and neck and everything else (including mood!). But my first ventures were back-and-forth.
I suspect that soozeq is right and you're trying to cast on too few stitches for the large circular needle that you have. 29" can hold a LOT of stitches.
For casting on, whatever method you use, make sure the stitch you cast on is NOT on the tip but on the fatter part of the needle. That should help solve the problem of stitches being too tight, and when you knit, be sure you slide your needle all the way through to the fat part of the needle to knit the stitch, otherwise it will be too tight also.
You are wise to take a break! Hang in there - it will become easier!
I though it said how far from the armholes to start the buttons? I rewrote mine to be done in one piece, so I can't look at that to help you.
As for the button holes - they are always larger than you'd think. You'd be surprised at how big that hole is! And if you use toggle buttons, which I did, then it doesn't really matter. I would not make it bigger, even in worsted. Personally. And you do want the buttonhole quite a bit smaller or it will keep popping off (experience speaking!)
I just made this for my niece and it turned out beautifully - if you follow the collar directions exactly as written you will find out they DO work and the collar turns out nicely. As Tephra said, you are increasing to get more length and then you will stitch that down to the front part where you didn't pick up stitches. If you don't do it this way your collar will not look like the picture. But, then again, you can do any kind of collar you want! - Knitter's Choice, as Elizabeth Zimmerman always said!