[stoneeZef]

Q2: Also, often, potential buyers of the land will not buy the land outright as they may not have the financial capacity. So they will opt to pay in instalments. In such an event, the ownership is only transferred once the last instalment is paid (which may be several years after the first). In such a case, would any zakat need to be paid at all on the year-to-year profit/appreciation since one doesn’t technically own the land? [QUOTE]

Its mentioned in Umdat As Salik:
hS.S If merchandise is sold during the zakat
year at a profit and its price is kept until the end of
the year, then zakat on the merchandise's original
value is paid at the end of that zakat year, but the
zakat on the profit is not paid until the profit has
been possessed for a full year.
(n: A second position in the Shafi'i school is
that the zakat on the profit is simply paid in the
current zakat year of the merchandise, just as one
pays zakat on the offspring of livestock (dis: h2.7)
in the current year of their mothers (Mughni almuhtaj
ila ma'rifa ma'ani alfaz al-Minhaj (y73),
1.399).)

Even if you receive 'advance payment' you are the owner of the land till the transaction is completed ie full payment is done by the buyer. So the land is still Zakatable right?
As for the advance payment, doesn't it come under profit?

I don't think we laymen can understand this, even after reading the rulings from the book. You will find a good ulema to clear this doubt.