Sorry to wait so long to reply. Things got a bit hectic around here. I broke down and called an electrician

And Im not real secure with Washington's practices when it comes to wiring. I checked the panel with these breakers off and still had voltage at this box. The electrician was not at all surprised by all the multiwire ciruits nor the way they were done. He said that it was normal practice.
He did however find that there was a wire from yet another circuit tied into this box [B)] He really didnt have an explanation for this but said if we just disconnected it and capped it off all should be well.
Its been a couple of weeks and the house is still standing. I feel a little better about the situation but, I will be changing out those breakers once this project is done. I understand how this works and he even adgreed to how dangerous the situation could be.
Kactuskid, to answer a few of those questions.
Yes one of the multiwire circuits is on a tandem breaker. (On the to-do list)
This is a main panel... there is a sub panel coming of of it holding breakers for 3 or 4 220v circuits.
As far as who wired the house, looks to me like original work that would have been done back in the 80's. Go figure...
Thank you so much for sharing your knowledge and for so patiently explaining all this Kactuskid. Ive learned alot from this experience and hopefully can make this a safer situation.
Thanks
Bogie