I have a simple Facebook question: suppose A (for instance myself) has friends B and C, but B and C are not friends. If I post to B's timeline, then can C view such post, either in their news feed or by accessing the post by some other means?
Under your privacy settings you should have the option of determining whether your posts are public or only visible to friends. If it's the latter, your newsfeed updates won't be visible to C by newsfeed. However, that doesn't override friend B's settings.
Friend B might have his or her settings set to censor or post by default all activity to his or her timeline. If you post on friend B's timeline and settings are "public", friend C (along with anyone else) would see that. If friend B reviews all timeline activity, he or she could determine whether that post is seen only by friends, friends on certain lists, or public.