I switched from brew to macports, and I have not experienced the first problem at all. In fact, I had more problems with brew, where some package needed to be updated that I did not want, and I caused a cascade of issues.

The second has also never happened to me. macports installs the packages into a separate prefix, and you just add that to the path, so I wonder how it could bork irretrievably.

Regarding instructions: for most packages, I found that just replacing `brew` with `sudo port` is enough, as most ports are available. And quite a few install instructions mention homebrew together with macports. I have not run into missing packages, but sometimes the ones that existed were a little out of date.