It depends on the filament. Increase the temperature on the printing plate and I switch off at least the side fan while it is printing the first layer. It sometimes blows something away before it sticks. Wipe the plate with alcohol from time to time to prevent it from sticking to fingerprints or other impurities. With PLA I use 55-60 degrees on the plate. With PETC it worked quite well at 80 degrees. You can also set the initial temperature and the temperature for the rest of the print separately in the settings for the filament.

I had the same problem at the beginning. Remove the plate and clean with normal detergent and water. I also use an adhesive spray for 3D printers, also ordered from Galaxus. According to the smell, it's probably just hairspray with a different label :-). I've never had the problem again. And I've already printed a few projects with it.
Hope that helps!

Yes, but that is also normal. After a while, the adhesive is no longer as strong. I therefore use the glue stick supplied or my favourite, cheap hairspray.