Several questions--carrying yarn, decreasing, increasing

Hello!
I am new to knitting and self-taught. I did the scarves, afghan, etc. now I am doing my first sweater (striped pullover). The stripes are 6 rows. Is there a way to carry the yarn up the side without having to cut the yarn and change color every 6 rows? Is this a good idea to do?

I have to do alot of increasing and decreasing. The pattern does not specify what stitch to do. Is there a standard? For instance on the sleeve, the instructions state to cast off 5 stitches and then decrease a stitch every other row at the beginning and end. Can I just cast off a stitch when i need to decrease? I really got confused with the increasing and decreasing that state slant left or slant right?

Yikes…maybe I have bitten off too much. Any help would be appreciated. thanks ever so much…Joy

When I decrease on sleeves, I generally knit two together. If you bind off one stitch, you tend to get a bump. It’s not a huge deal, but it will be easier to seam without bumps. Also, since a sleeve is seamed, the lean of the decrease isn’t critical, in my opinion, either.

As for the stripes–if each stripe was only a couple of rows, I’d definitely carry it up the side. You can bring the yarn up the side by making sure the working yarn comes up from under the other strand and pulls it up the side. You have to see if it makes the edge too thick, and it could affect how easy seaming will be.