Beginner Questions Washbasin & Faucet Planning

Hello,

I have a few essential questions that I would like to have answered ;)

Let's assume I'm planning with a faucet from the brand Duravit.

What exactly do I need to know to install it "properly"? Can I use any random mounting element, e.g. from Grohe, in the drywall? Does it matter which siphon or angle valve I use?
I am reluctant to rely solely on the advice in specialty stores, as in my opinion the sales aspect always takes precedence there.

Now let's come to the washbasin.
I would like to have a washstand. I assume that due to the non-hanging installation, the weight of the washbasin including the full contents must be completely supported by the washstand along with the legs, and that this is not a problem.
My installation approach would be (layman’s assessment):
- Attach basin to washstand and seal with silicone
- The washstand (standing) is attached to the wall. Here I am thinking of "gluing instead of drilling" so that I don't have to make extra drill holes in the tiles. The force vectors are primarily in the xy-plane. I assume there will be no tension, negligible compression, and if so then shear forces.

Thank you very much for your answers!
Hauke

EDIT: Okay, so I mostly need a single-lever mixer tap, which depends on high or low pressure.

Yes, you can do it that way. Shut-off valves, siphons, etc. are standardized. There is nothing wrong with that. Only different design variants. Namely the usual pipe siphon, bottle siphon, dry siphon, and of course the concealed version.

Hi

You can use any X mounting element. Install the dimensions of the connections according to the specifications of the manufacturer of the bathroom furniture and the porcelain. Washbasin faucet depending on the water supply.

Why do you resist asking in the specialist trade/specialist shop? Because of profit-making intent?
There are even people who earn their income as project managers.

Olli