Mtka - Manellopgar Toolkit Advanced Deformers With Geometry Nodes [Bend, Twist, Taper, Stretch, Shrinkwarp]
A small sample video: https://youtu.be/H0uCcc0apmk
No, they are Geometry Nodes Nodegroups that you can use with any geometry or as one more modifier.
3.3, 3.4 and above.
If you have doubts, please check this video: https://youtu.be/S_Z9uM8p9mo
You must first add sufficient subdivisions for your object, otherwise, the nodes may not work correctly. You can either add a Subdivision Surface modifier before the geometry node or add a Mesh Subdivide node in the geometry node with an appropriate level selected. If something does not work correctly for an object, please verify whether you have added enough subdivisions for that object.
Yes, here I attach a video where you can see that I combine different Bend deformers with one twist deformer, the same applies to all modifiers.
An example video here: https://youtu.be/-OIK_8BVl6U