When I went (Feb 2013) the refuge was most frequented place in Margalef itself. Good coffee, juice and bread/cheese/ham/fruit breakfast. Evening meals looked good too, but we didn't get round to eating there. They also do bottled beer and wine and have a nice, big eating/hanging out area. The locally produced topo is available here - a local activist runs the refuge. Older web info I looked at before we went had the old address for the refuge - the current one is right on the main road, the other side (of the road and the river) to El tres Pins hotel. The coffee isn't bad at El tres pins, and they do fried things in white bread with chips. The best place to eat out is at Ca Calbert, up the hill in the village. Really good home cooked food, run by two very friendly spanish ladies, very reasonably priced. Small and restaurant-y, rather than pub-that-you-eat-in, but not posh. They also do accomodation. Couple of bars in the village, pretty 'local', but friendly and good, cold beer. There's a local shop too, not extensively stocked but you should find fruit, veg, canned fish, beer and factory cake. All of the above are within about 200 yards of eachother, in various back streets up the hill from the refuge.
Most people doss up near the dam, but various roadside pull offs were full of vans too.
Closest town with a super(ish) market is Cornudella del Montsant, near the turn off to Siurana, so 45 minutes or so of windy road away from Margalef. There's a good bakery that does nice coffee, and a winery (both on the main road). It's very close to the Montsant crags, (quiet, very picturesque and lots of mid-grade wall climbs - in the Tarragona climbs guide). Several reasturants and bars, (we didn't go to any , but they looked ok).
Hope that's of some help.
