Pave the driveway, carport later - procedure?

Yes, metal sheets are indeed quite loud and important. When you install metal sheets, put an underlayment membrane under the battens, because if you install anti-condensation metal sheets, they sweat just the same and the water then collects on the underside of the sheets, where the fleece is, and the fleece then becomes wet. My tip as a roofer: put wood on top and cover with 2 layers of roofing felt ;)

misspell? :D;) I assume it's autocorrect.

So that means no trapezoidal sheets at all but directly covering with wood?

abscheißen? :D;) I assume it's a typo.

So no trapezoidal sheets at all but directly covering with wood?

Yes, it should say "abschweißen." Sheets are not so good, better to weld them shut ;) So put on 24mm tongue and groove boards and then weld shut with 2 layers of roofing felt. Then you have about 30 years without problems, speaking from experience...... I'm a roofer ;)

as for the tongue and groove planks and the roofing felt, that sounds like a plan. It's just the welding off... that's putting me off right now... so much for expertise ...

Does anyone know the drainage channels called C250 for 25t or C125 for 12.5t? They can be found on e*bay... seems to be a Polish product.

C250 or 125 is only the load class and not a name