I am not sure about the first question you asked, especially with her salary being higher than yours. Since the home was purchased prior to the marriage and the marriage was so short, I’m not sure that she would have a “claim” to the home. Since she does earn more than you, it’s possible you could request post separation support…but I will leave that for an attorney.
The second question is if you WANT to help her out by furnishing her place you can. You are not obligated to help and I suggest you make sure that there is a separation agreement in place prior to her setting up credit for furniture and/or appliances. You still have the date of separation but in your current situation, I wouldn’t take any more chances with the credit. You said you are living in a pretty much empty house, does that mean that she took most of what you two had as far as furniture? Since you paid the security deposit, what else is she expecting that you pay for?
The last question…you are not responsible for any debt prior to marriage. You are responsible for half of any debt accrued during marriage regardless of your knowledge of them. Unless you either have the debts specified in a separation agreement that she is solely responsible…or you have the court decided that this could be considered separate debt due to the length of the marriage. You are not responsible for any debt after the date of separation unless you are increasing marital debt. If she has increased debt since the date of separation, that would be considered separate debt and would be her responsibility.
I suggest getting together all the information, and consulting an attorney for the separation agreement.