Hello and Welcome Drachonite!
I firmly believe one needs to understand Voltage and Current fairly well to be able to build Energy Machines. Voltage is Charge Separation and Current is Pumped from Source, where Source is Outer Orbital Electrons in the Valence Band.
Voltage
Voltage is the total number or Charge, Elementary Charge, but I prefer Free Electrons, that have been separated, on the Conductor, where one Terminal has a greater proportion of Free Electrons compared to the other Terminal. This is called the Potential Difference in Charge. One Volt is equivalent to: 6.241509 x 1018 Electrons.

This means, if we were to have a Potential Difference of One Volt on a Battery, one Terminal has more Free Electrons, compared to the other Terminal, by 6.241509 x 1018 Electrons.
What causes Electrons to move to this Terminal?
Elementary Charge
Elementary Charge is just the Electron that is in a High Energy State.

The Electron, if it is exposed to certain conditions, it will move up in Energy States. See the above image. The Electron eventually moves right up to the Outer Orbital, and the Electron then has the potential to be knocked out into the Conduction Band.
The Electron, because it has Charge, it has a Magnetic Moment, which, when combined with its intrinsic angular momentum (spin), dictates its behavior in quantum systems and electromagnetic fields.
To expand on the physics: an electron has both an electric charge and an intrinsic property called "spin" (a type of quantum angular momentum). In classical physics, a spinning charge generates a magnetic field. While quantum mechanics tells us the electron isn't literally spinning like a top, this combination of charge and spin still gives the electron its intrinsic magnetic dipole moment. This tiny magnetic field is exactly what makes things like MRI machines work, and it is the fundamental reason why materials like iron can be magnetized.

Of course, under the right conditions, we can Accelerate the Electron down the Wire:
Current
The Rate of Flow is what defines Current. If we want to measure One Ampere, we measure: 6.241509 x 1018 Electrons past point P1 in one second.
The Total Amperes measured boils down to the total number of Free Electrons that can move through the Conductance Band.

Only when you turn on the switch and the globe lights, can you then, observe the effects of Lenz's Law, the Opposition of Magnetic Fields, the Opposition of Currents, which in turn IS the Drag on the Rotor Shaft, which is the reason Input Power goes up under load, and the reason for the second law, the conservation of energy laws. Lenz's Law is a given and everyone has seen it in one form or another.
Understanding Current is a very important requirement! If we truly understand Current, we can see areas that open doors for Smart Techniques to introduce Asymmetrical Electromagnetic Induction!
Asymmetrical Electromagnetic Induction
Asymmetrical Electromagnetic Induction is the exact opposite to the well known Electromagnetic Induction we all know very well today!
Example of Symmetrical Electromagnetic Induction: The Conventional Transformer is an entirely Symmetrical Device; an Input Coil, an Output Coil, Symmetrical Forces between Input and Output Coil, this is why no one can use a Symmetrical Device to get an Energy Gain, because they are inherently a Closed, fundamentally restricted devices where: Output = Input - Losses
$$ P_{out} = P_{in} - P_{loss} $$
Here is a breakdown of the variables:
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$P_{out}$ represents the output power.
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$P_{in}$ represents the input power.
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$P_{loss}$ represents the energy lost to heat, friction, or other inefficiencies.

If I say to you: "If you load this Transformer more and more, so the Output Current increases: Is, the Input Current: Ip must go up to compensate." do you see the very tight correlation to Lenz's Law and the Currents in Opposition?
This is where: "Partnered Output Coils" come in and why Asymmetrical Electromagnetic Induction change the Stage we work on and why we can get a Gain in Power.
If I propose to you: "What if, your Transformer did not Oppose your Input Coil directly, and the same Opposition was still present in the system, but it was redirected to another Coil, instead of your Input Coil?"
What this means
In any System, by shifting the Units of Force onto a different Source, we can still do the same total work, but the Force in the System is not directed back on us! We shift the Force and redirect it to another Source. This is what "Partnered Output Coils" achieves. The trick is, one needs to get the Voltage up, we need to trick the "Partnered Output Coils" into both seeing a specific Voltage, then we can make the "Partnered Output Coils" do ALL or the Work for us!

Answering your Questions
To answer your questions directly, once you understand the above very simple physics, is quite easy.
Here are my questions.
How do I get to the 10X amps that the PDF mentioned?
What is the coloration between the core watt rating and the wire amp rating?
Would the step down be limited to the 2kw of the step down transformer?
Would using 0.9mm wire rated at 10amp make a difference?
Would I need to ferrite with a higher KW rating?
- Amperes are Pumped from Source by Opposing Magnetic Fields, but the Equation: I = V / R holds, so you must have a Voltage and Resistance of known values to get Current I.
- This question has answers through out my Forums pages. Please study the material provided.
- Working this high in Voltage is not recommended, I have never recommended High Voltage, I recommend starting with 2 or 3 volts, slowly move up from there if needed.
- Yes, but this is a way later on question and is not important at the start.
- No, Ferrite may be an option for High Frequency. Its not a requirement, use any core you can, any coils you can.
I have a few guides here in these pages, and in the pdf, I do provide basic starting recommendations, perhaps a review may be helpful. I suggest Low Voltage, Small Coils, and a few simple components, then, replicate Experiments I have already shared, learn the very basic stuff I have shared, then you will understand the above, and then you will see why the Opposing Magnetic Fields are important and why Partnered Output Coils give Humanity a new Physics, Asymmetrical Electromagnetic Induction, the next step after Symmetrical Electromagnetic Induction!
Best Wishes,
Chris