You can try to write the collection agency a goodwill letter asking them to delete the account. May or may not work. If you list the name of the collection agency, someone may have tips to help you deal with them or good contact info for you. For the authorized user account, you can have your husband call up and remove you as an authorized user (you may be able to do this yourself as well). You could also dispute with the CRA that is reporting the card, as the account is not yours, but save that for the last resort and try to go through the card issuer first.
As for which score they will use, who knows. You can aske the dealer what score they will pull before you apply. They may not pull any of the scores you have access to but might pull auto enhanced FICO scores. Just have to ask them what they do.
@Anonymous wrote:I got my scores here. myfico.com
Good. Then you know they are accurate. 
From a BK years ago to:
EX - 3/11 pulled by lender- 835, EQ - 2/11-816, TU - 2/11-782
"Some people spend an entire lifetime wondering if they've made a difference. The Marines don't have that problem".
