Question
alright, clearly I need to see a chiropractor...which type im not sure of yet, but how could I be?  I dont know anything except of what youve told me.  
anyways, So you can't even give general probably advice for my back?  Example-shouldn't I  do sit-ups or deadlifts (or any lift) with my back straight and my legs supporting?  wont keeping my back straight and using my legs to do things...and i know you dont like this word...better prevent me killing a disc or something?  I mean, you cant get too succinct about your posture because then it will be speculating too specifically, and possibly missing the boat anyways...
Followup To
Question -
Just fyi when I said arching my back in the wrong direction I just mean bending it in the wrong direction, not arching it back and sticking the chest out like they tell you to do in instructional safety videos

Answer -
Jeff,

Thank you for the additional clarification.  
Please read my response to your original question(s) as the additional information has not changed my response.

James W. Healey, DC

Answer
Dear Jeff,

I sense our exchange is not providing you with the answers you desire, even if it provised you with useful information otherwise.  I will again mention that there may be others, such as a personal trainer, who may wish to observe you and advise you.  

Best of luck in your weight lifting!

Sincerely,
James W. Healey, DC