In terms of misconduct, I imagine it can be mollified with adequate references and noting from where you are borrowing. If it is clear that it is just setup material and not repeating the same results, you are including material for the convenience of the reader and or to make the paper self contained.

At this writing, more and more use is being made of repositories like the ArXiv. I think it quite reasonable (contrary to Mariano's sentiments above) to make a 'travel version' of your setup which is compact and condensed for inclusion in a paper, and repeated for several papers, all containing a reference to an expanded version of the setup as part of an ArXiv paper which includes more motivation and discussion for the new reader. This way you can accommodate both first-time and more experienced readers of your material, almost all of whom have access to ArXiv.

Gerhard "Make Your Work Go Places" Paseman, 2017.02.16.