Necessary processing steps and their order? Registration before or after dwipreproc?

Hi Max,
thank you for your help.
I have read both tutorials and already did the “Beginner DWI Tutorial”. But now I would like to do the Multi-tissue constrained spherical deconvolution approach. After reading the documentation I still have some questions:

1.The documentation says that I need to do a rigid-body registration between a T1 and the DWI images. Because there is no information how to do it I guess I just have to do the mrregister command with the rigid option?
2. Do I have to use the T1 image as template or as moving option? I guess as moving option?
3. Do I have to preprocess the DWI’s and the T1 before coregister?
4. I read that Eddy already includes the b-matrix reorientation but when I do a registration afterwards, do I need to reorientate again my b-matrix or is it just necessary for subject motion correction? I guess when I coregister just the T1 to the DWI’s I do not have to reorientate the b-matrix?
5. You suggested me the dwibiascorrect option. Is it also a necessary step cause I could not find it in the pre processing section on the documentation website?
6. I also try to find a solution by searching in the forum, but this confused me even more. In both i.) ii.) questions they were talking about freesurfer and flirt?

So I am just wondering if I have to do additional steps in my pipeline? Otherwise I would do it the way it is suggested on the documentation website?

  1. Do dwi denoising, dwipreproc, dwibiascorrect
  2. Registration of T1 with DWI (mrregister)
  3. Do 5ttgen, dwi2response
  4. Do dwi2fod msmt_csd

Sorry for all my questions but its my first time processing such data.
Thank you
Best
Max