On posting
1) Top posting means I don't have to scroll through a ton of crap to read
the new message. However if I desire I can easily see the context by
scrolling down.  If I read this in digest mode where I only read the last
message in a thread, then yha, bottom posting would make more sense.
2) Use a threaded email client that removes the extraneous copies of prior
content and you never have to worry about this again. All messages are
either top or bottom posted depending on how you order the thread.