Income earned before date of death goes on the final 1040, which is why you don't need to read any wills or trusts, but you might need to see the death certificate to verify you have the right date.  It doesn't matter whether the assets passed in any of the three possible ways:  Probate, joint tenancy or beneficiary designation. 

No, that's now how it works.  Taxes get paid first, then administrative expenses and finally unsecured creditors.  Similar to bankruptcy.  There may be survivor allowances (similar to exempt property in bankruptcy) that come before creditors also.