Legal Question in Family Law in California

As to your first question the answer is, "no." You have the reimbursement structure backward. Reimbursement is for separate property used to pay a community debt, not the other way around. Theoretically you could claim reimbursement for 50% of the payments made before marriage, but in the absence of a tenants in common agreement or prenuptial agreement, it would be a "he said, she said" as to whether those payments were a gift, and/or balanced by expenditures she made. The most likely outcome if it were disputed is you would be entitled to 50% of the principle paid, but not the interest. Since that was early in the loan, when each payment goes mostly to interest and only a little to principle, that amount is not likely much.

You are correct as to the impact of a refinance. However, that would not change anything from what is happening now, which is community property (your income) being used to pay separate debt (her 1/2 of the mortgage). Once you are married, only separate property used to satisfy community or separate debt is reimbursable in divorce. (Where that most commonly arises is when post-separation income is used to continue making payments on community debt before the divorce is final).