Enter your UK registration in the search tool for a match to your vehicle, or check the tyre sidewall for the size (for example, 255/60 R18) and search manually by tyre size.
Often, yes - Amarok tyres commonly require a higher load index than a standard car tyre, so you should match (or exceed) the manufacturer-recommended load rating shown in your vehicle handbook or via reg lookup.
It is best not to, especially on a 4x4 Amarok, because different tread patterns and wear levels can affect handling and rolling circumference; keep the same tyre type and similar tread depth across each axle as a minimum.
The UK legal limit is 1.6mm across the central three-quarters of the tread around the entire tyre; many drivers replace earlier for safety, particularly for wet-weather driving.
Select your preferred fitting partner at checkout, pick an available appointment slot, then attend with your vehicle (and locking wheel nut key if needed); the garage fits the tyres and can usually dispose of the old ones.