re. the triangle in a rectangle construction aspect of your question -- what method(s) have you used thus far, and what approaches do yo like?
I was recently in a swap where one participant asked us to make paper pieced rectangle/triangles, which was not my favorite approach. I like using a tri-rec ruler-- I consider it a good investment for getting precise piecing. There are a couple of tutorials online that suggest using a printed guide, but most in the group had significant issues getting accurate final blocks.
So - my suggestion, as you have quite a variety of blocks in your design -- make one trial block and see how it goes and where you run into issues, then problem solve from there.