Portland is in a unique spot right now working through some rental regulations (both city and state-wide) that have the market in a bit of a tizzy...some are pulling out, some buying in, and some are just sitting and waiting.

Anything over 30k in rehab costs is a bit more complicated of a transaction and requires more fees and regulations. 

Too much turnover and too little knowledge of their own procedures for MY comfort. 

Not only that but you need to know the cost of material and labor, in that specific area, plus regulations, permits, SID's, and something else will inevitably pop up.I would at minimum pay for a contractor to walk through it without you there.

I’ll check the regulations for S8 and I’ll plan ahead.

In the meantime, you can join a property owner (landlord) association like I did in order to educate yourself on state laws and procedures.

BUT, the permit process is town/city regulated, so yours may be different.

Not only the STR market is not yet mature it will always have some sort of instability for several reasons; cities regulation change making big increase or decrease in a location leading to new hosts.

AU laws are certainly much more stringent and regulated than the US. 

Yes, if they follow proper procedure for changing the CCR, likely a vote, they can change the rules.