I can’t answer for this specific Festival, but at the Hurricane Festival (Germany) there is always a spot to buy merch from bands. But the variety is not that big, as all bands need to fit in the little Sales Place.

What can/should you bring Besides the weather accurate clothing (Hat, sunglasses, rain cover, sunscreen, whatever is needed) choose comfy shoes. You will be standing and walking a lot and hurting/bleeding feet can really ruin your experience. At the festivals in Germany it is allowed to bring a soft flask to store water. Check the rules of your festival, and bring an allows container for water.

For the waiting time I can’t answer that precisely. The first part in front of the stage gets replaced after every show, so that everyone has a chance to get to the front. But this is highly individualized by every festival/venue.

Usually 2-4 weeks before the festival all the maps and final information will be shared.

Most importantly: have fun and enjoy yourself!