check if your state allows recording audio without consent - your guests will want to sue you.If they dont want to sue you, all they have to do is report you to airbnb and they will ban your listing without even asking you. then you'll spend months trying to get unbanned.

Its common for PMs to have a budget threshold for repairs where they can approve without your consent.

i never signed it because I didnt do the work, but it was a part if the bid,  the foundation company would likely require the neighbors  signed  consent because they would also be named in a lawsuit.   

Till now I did only direct mail, now I would like to start email (pull a list from propstream and skip trace the email address) but if I understand correctly I'm not allowed to use these email addresses without consent?

If a party gives informed consent, then the deal is good...IMO. 

So that was against the original lease which requires landlord's consent before subleasing. 

Further to that, it can be done unilaterally, that is, without consent of the seller?

Sublet possible with landlord consent

You'll need to deal with the bankruptcy trustee (or at least obtain his/her consent) regarding any transfer.

In Iowa you have to consent to dual agency meaning consent to the brokerage having both the buyer and seller in a transaction as a broker and salesperson have fiduciary responsibility to the their client and when they are helping 2 clients on the same transaction there can be perceived or possible real conflict of interests.