Q5.0.2: I do not like cc-mode. How do I use the old c-mode?

Well, first off, consider if you really want to do this. cc-mode is much more powerful than the old c-mode. If you’re having trouble getting your old offsets to work, try using c-set-offset instead. You might also consider using the package cc-compat.

But, if you still insist, add the following lines to your init.el:

(fmakunbound 'c-mode)
(makunbound 'c-mode-map)
(fmakunbound 'c++-mode)
(makunbound 'c++-mode-map)
(makunbound 'c-style-alist)
(load-library "old-c-mode")
(load-library "old-c++-mode")

This must be done before any other reference is made to either c-mode or c++-mode.