How do I see and adjust presets?

Presets are just a convenient and standard way to move the standard adjustment sliders to particular values. It is those adjustments, not the preset itself, that make a difference to your photo.

The same difference happens regardless whether you've manually moved an adjustment to a certain value, or copied that across from another photo, or used a preset to set it to that value.

Furthermore if any later preset or manual change has further altered relevant adjustments then it no longer makes sense to talk of the photo as "having" that preset applied any more. The record of its usage in the History has to be considered together with all the other History steps, to explain how the photo currently looks.

Some presets can be modified in their % effect immediately after they are used - before dpoing anything else - but this is again merely a matter of what setting the actual adjustments concerned are to adopt. Say a preset is going to set Exposure to -1, and then you choose to moderate that preset's action to 50%. This just means that the Exposure slider moves half the distance from whatever its present value is, to the value of -1 that is written into the preset. Exactly the same as if you had manually moved the Exposure slider to this final setting. That is what the photo goes forward with - there is no ability to later change % action of the preset. A preset is not any kind of persisting "thing" that would be further adjustable, or listable - it is a momentary past "event" in the image's History.

Analogy: knowing something perhaps from school, or perhaps from encountering that fact somehow else. We can't assess or extend our current knowledge by reconsidering what school lessons we had as a child (some of which information was later forgotten or corrected or superseded), nor by reviewing our other past experiences for that matter.

We work from, and update as needed, our present situation - which results from a combination of all that.

...

1) How do I see which presets are applied to my photo?

...
By @neonmamacita

You'll see it in the History section on the left side panel in the Develop modul. There are you see all steps that you have made during the editing of your image.

...

2) Is there a way to switch off and on which presets are applied? 

...
By @neonmamacita

No.

...

3) Can I adjust the strength of these presets? ie. is there to apply WN02 at 100% or at 10%?

...
By @neonmamacita

Yes. But this possibility must be set at the creation of the preset. During the creation process you have to enable the "Support Amoint Slider" option.

Then you can set the amount after you have assigned the appropirate preset

More infos you'll find also here: Work with the Develop module in Lightroom Classic