I can confirm that it's possible to have more than ten houses on one single wizard and more than 30 houses on an account. Three of my highest level wizards all have ten. I think my Fire might even have eleven houses because I recently bought her one of the Mirage apartments. (I used to spend gold on houses in the crown shop when hitting the gold ceiling over and over. Now I just hatch pets. )
A couple of Wizard101 You-Tubers that I watch each have two or more full pages of houses on their highest wizards. So that's at least 16.
I don't know what the max is. As long as you buy the extra housing elixir, it can be added. On my account I have 3 wizards. One has 21 and the other two each have 19 places. Like Fresta when the gold hits close to max I buy a house/place/castle. Then I spend the gold on furnishings. Some housing items in the crown shop can be bought with gold,,,but you have to remember to hit the gold button to pay with gold. It's so much fun decorating a new place. Keep in mind each wizard is only allowed one of each place. So if you buy say a life house(treehouse) for a wizard, you can't buy another life house for the same wizard but you can buy a life house for another wizard on that account.
)
Alia Misthaven