Minecraft /give Command Generator

Nearly always because the syntax does not match your Minecraft version. In 1.20.5 the command changed from carrying extra data in curly braces to using item components in square brackets. Neither form works on the other side of that line, so pick the right version at the top of the generator and the command will work.

Item data moved from an NBT tag to item components. An enchanted sword used to be written with an Enchantments list inside curly braces, and is now written with an enchantments component inside square brackets. It is a different syntax rather than a tidy-up, so older command generators produce commands that simply fail on current versions.

Yes. Commands skip the limits that apply in survival, so you can hand out Sharpness 255 if you want to. The generator shows the survival maximum next to each enchantment for reference but does not stop you going past it.

Yes, for the same reason. Sharpness and Smite cannot go on the same sword at an anvil, but a give command will apply both without complaint. Whether that is a good idea for your server is another question.

In game you need to be an operator, and the command starts with a slash. From the server console you run the same thing without the leading slash. On an MCHosts server the console is in your control panel, so you can paste it straight in without joining the game.

Yes. The picker holds the full item registry, laid out in the same categories as the creative inventory, and the search box cuts across all of them at once. If you know part of the name or the id, typing it is usually faster than hunting through the tabs.

Spawn eggs are ordinary items, so they work like anything else. Open the spawn eggs tab or search for the mob by name. Bear in mind that placing one needs the mob to have somewhere valid to spawn, so an egg that appears to do nothing is usually a light or space problem rather than a bad command.