Hmm. Well I sew pretty much anything. Fleece works fine no problem at all. I also made slip covers for our chairs using a thicker furniture fabric without a problem so its pretty heavy duty. I have never done any embroidery or beading on it so i haven't a clue if you can.
I'm not as good as i used to be, too many years without 4-H
You can find patterns for dog stuff at joanns fabrics. Simplicity and McCalls have them i do believe, but they're pretty basic. I'm by no means a pro, but i started with a baby t-shirt and then folded it into the correct proportions. Like folded the stomach up so he doesn't pee on it, and shortened the sleeves. Then took it apart and use the pieces for my basic t-shirt pattern. The picture was my very first attempt at a jacket and the seams are pretty sucky, but it was more a test then anything.
I'm sure there are others on this site with ALOT more experience than i have though best of luck!