IAS 12

Because, on sale at the revalued amount, a profit will be achieved resulting in a tax charge. Settled on sale of the asset Because the revaluation is credited to equity

No, capital allowances (are they available on land - I'm not sure - you'll need to ask the F6 tutor about that!) will, if they apply to land, only be given on the original cost. I THINK! This is way beyond F7 and I don't remember anything like it at P2! Sorry to be non-definitive about this

If you make a gain on the land investment, you'll pay tax on the amount of the gain

If you buy something and then sell it for the same price, why would you expect to pay tax? If it has attracted capital allowances, you pay tax on the difference between sale proceeds and tax written-down value