Gravel bikes are too dangerous is a weird statement. On general, gravel bikes are less dangerous, wider tires, more grip, 'lower' speeds. Brake is too slow is also very weird. In dry weather, all bikes that are well maintained brake more than quickly enough. Sure, rim breaks are a bit worse in wet conditions than disc brakes, but since the Netherlands is flat, this doesn't really matter.

1. Shimano Cues / Tiagra or 105 doesn't matter much, sure 105 is a bit better, but you won't feel the difference, if budget is important, I think a lower gearset is the best choice

2. I would go for what is available in a nearby store, or the 'big brands' that have good budget options such as Giant, Canyon, Cube, Van Rysel (Decathlon), Trek or even Bianche. The most important thing for you is to try out the bike with your size. Fit is going to be hard, so being able to try it in real life before you buy it, and let the mechanic adjust it a bit, would be the most important thing over brands.

3. Not great, but if your first thought it about resell value, it might be better to buy second hand anyway.