Laws vary by State, so ask a tax official. But I believe that only the portion of your maint fees that cover the property tax would be deductible on your Federal return as taxes paid. I am a new owner and owed no fees for '07, but I believe DVC sends you a tax statement, could an older member verify this for the OP??
I am in no way a tax expert, but can tell you what we did.
When we got our annual dues statement, it breaks apart what goes to property taxes and other expenses. We claimed the small portion that goes to property taxes. We own 390 points and of a $1600 dues bill, we only claimed about $400 of it.
As for interest, we financed through our mortgage lender, not through Dis. Ours was tax deductible. I'm assuming what you finance through Disney is as well, but again, I am definitely no tax expert.