The requirement is for the licence number to be displayed on the Homeaway website as well as to put a plaque somewhere prominently on the wall . . .
Yes indeed – a fine balance between following the dream and not finding loads of expensive issues . . .
On the rental income sadly this has to be declared less costs to the spanish authorities on a two monthly or quarterly basis and to comply with another law all your guests over the age of 16 [I think] need to provide their personal details which your agent would need to supply to the local guardia [but this can be done by email].