Yes, there are various sizes and thicknesses.

Since manufacturers can use different crates, different sizes of sieve boxes can be found.

Such a period cannot be given. Parts lifetime varies depending on wear, some depending on the duration of use.
You can choose proven spare parts by working with the right supplier working with catalogs and technical drawings.

If it is both, cheap and of poor quality; negatively affects the performance and production of the machine.

Some parts are not under warranty because they are fast consumption parts, while some parts have a warranty period of 6-12 months.