I recommend this website: http://www.freelegalaid.com/nav/Oregon/eviction-and-unlawful-detainer
[In accordance with the Avvo community guidelines, this communication does not constitute "legal advice", nor does it form an attorney-client relationship.]
Your last months rent deposit cannot be applied to a month that is not your last month without your landlord's consent. For a posted 72-hour notice to be effective it must (1) also be mailed and (2) there must be a written rental agreement allowing for service by posting and mailing. I'm concerned that you are making mistakes in trying to navigate these issues on your own. Issues of concern to a housing inspector are not necessarily going to be a defense to a non-payment of rent eviction--it depends on the issues.