Halacha 1 states the seller can redeem his house 'every twelve months from the sale' — a private redemption year from the transaction, not a calendar year.
Question 2
Who can redeem a house if the seller can't?
Halacha 2 emphasizes that relatives cannot redeem a house in a walled city — only the seller himself, if he has the means.
Question 3
What happens to a house if Jubilee occurs?
Halacha 9 explains that the verse 'it shall not leave in Jubilee' applies even before the house is 'permanently acquired' — the house remains with the buyer until the end of the redemption year or until the seller redeems it.
Question 4
What is the minimum area for a house?
Halacha 12 states that a house without four cubits by four cubits is not considered a 'house' for this purpose and cannot be permanently acquired like houses in a walled city.
Question 5
What determines if a city is 'walled'?
Halacha 15 rules that we follow 'a wall that was built in the days of Joshua ben Nun' — a city that was walled during the conquest remains in this status even if its wall is destroyed, and vice versa.