Proper way of making documentation via Acrobat

I am having trouble with pdf format. I want to make documentation, which is able to have vector graphics(diagrams) and formated text. Now I use the tools Adobe illustrator, Adobe Acrobat DC and Word, but am not shure if this are the right ones. My troubles are:

1. When I make some diagram in illustrator, save it as pdf, open it in Adobe Acrobat DC for edition, add some Ms Word formated text(this can be skiped) and move the diagram in current place, then save it in the same pdf, and open it again in illustrator - the structure is not the same(below images - the arrow is separated in two parts, the text is not text box any more but single lines of texts). So my question is should I keep the raw illustrator files.

Adobe illustrator:

Adobe illustrator after moving diagram in Acrobat and save it in the same pdf and press 'keep changes':

2. Is Acrobat made to mixing texts, graphics,vector graphics and etc(from different formats) in single pdf file?
3. How to edit the vector diagram I made with illustrator, after Acrobat changes(moving it around and save it), like the way I would do it before Acrobat changes?
4. Should I rely on pdf documenting or maybe I should think of HTML with SVG equivalent?

I just don`t understand how the profesional documentations are made in pdf, and after that are easy to be edited.