I've not seen any mention of it costing to change house style, but there's not a huge amount of information on how towns 2 will work yet. I would guess however that similar to how towns 1 houses worked we'll be charged eventually to change house style.
Have your friends picked a plot and house design yet? I'm not sure they'll show up unless they've selected their plot and house type.
It means exactly what it says to evict someone, you're kicking them out of your neighbourhood so they can't have their house there any more. And no, you don't get rent for someone building in your neighbourhood.