You and your brother have no legal duty to do anything with your father's estate.
Generally, his creditors must be paid (if they file valid claims on time) before anything is passed on to the heirs. On the other hand, your brother, being a minor, has a priority claim against the father's estate that will take precedence over those of the other creditors.
If all the cash your father had is $3k, frankly, all of it likely will be paid to the attorney if your family hires an attorney.
The creditors likely do not want "tools, scrap material, junk car & boat" as those things likely would cost more to sell than just leaving them alone.
Anyone that is interested can open probate for your father. So, any of the creditors can open probate if the creditor thinks there is something to get from the estate.
"Does the landlord have rights to empty his property to rent again?" In WA, the death of the tenant or landlord does not legally end the tenancy. That is, the person handling your father's estate can claim that the tenancy has not ended and continue occupying the rental provided that rent is current. Given that rent appears to be overdue for several years, no one likely would want to claim that the tenancy should continue. If your family does not object, there likely is no one else to object when the landlord re-takes possession of the rental based on abandonment.
Your brother may be entitled to Social Security benefits if your father had earned enough SS credits. Your mother can check with SSA whether your brother has any SS benefits. More information is at www.ssa.gov . The sooner an application is filed, the sooner your brother can get some money.
The bank holding the money will forward the money to the State's Unclaimed Property office after three years of no activity in the account. Whoever is legally entitled to the money can get the money from the Unclaimed Property office at any time. The website is http://ucp.dor.wa.gov/ . So, one option may be to wait to claim the money from the Unclaimed Property office. Most commercial creditors are not going to start probate in an estate such as your father's.
Your family can get an initial review with an attorney and then decide what to do.
You are right, that is rather complex. It might be worth your time to hire a lawyer, which can be done with estate funds. The $3,000 in the bank account would probably be enough to get most of it done. One way or the other, the estate has to be taken care of.
This posting is for informational purposes only. It is not legal advice, nor does it establish an attorney-client relationship. For more information, please visit www.justinelderlaw.com.
The complexity of the issues makes it important that your family consult an attorney to assist in clearing the debts or eliminating them because of the insolvency of the estate, claiming any exempt personal property and clearing out his apartment so it may be re-rented. There is also an issue because technically your brother is a minor. You need legal help.
The above answer is not to be considered legal advice and should not be relied upon as such. You should consult your attorney for specific legal advice as to your individual situation.