This is a screw cassette (not a plug-in cassette). You don't need any tools to lock the cassette because you tighten the cassette when pedalling. To remove the cassette you need a cassette puller. This should be in your kit. I use the ParkTool FR-1.3. With a spanner you can loosen the cassette in an anticlockwise direction. You can also clamp the cassette puller in a vice, so you have a bigger lever.

Yes. FR-1.3

A sprocket has a hub with a screw thread, i.e. the sprocket is screwed onto the hub body. A cassette is mounted on a freewheel body that is screwed onto the hub and fixed by means of a lock ring. From a mechanical point of view, the two systems are completely different and not compatible. Many sprocket combinations with different numbers of teeth are available for cassettes. The bolt-on sprockets are slowly dying out and the number of gradations is limited. Cassettes are the way forward.

A sprocket has a hub with a screw thread, i.e. the sprocket is screwed onto the hub body. A cassette is mounted on a freewheel body that is screwed onto the hub and fixed by means of a lock ring. From a mechanical point of view, the two systems are completely different and not compatible. Many sprocket combinations with different numbers of teeth are available for cassettes. The bolt-on sprockets are slowly dying out and the number of gradations is limited. Cassettes are the way forward. as it has been answered here https://www.galaxus.ch/de/s3/questionandanswer/was-ist-der-unterschied-zu-shimano-tourney-freilauf-kassette-mf-tz21-7xhttpswwwgalaxuschdes3products-194350?productTypeId=805 has already been answered