I have only had my luggage take an earlier flight once, and it was not from AMS. These days with positive bag matching this is unlikely to happen.

There are a couple of food outlets within the terminal, and many more outside the secure area. The ones outside do look more appetizing. In fact the entire non-secure area looks like a mini-shopping mall, while airside it looks like a good airport. Very different atmospheres.

As for sitting areas outside of the lounges, it is easy to find a comfortable, relatively secluded set of lounge chairs airside, especially on the non-Schengen side. Nothing much outside on that front.

In fact with 4.5 hours there is enough time to go to Amsterdam by train (15-20 min ride, up to 6 trains per hour) and have lunch there.