Frostbaby, yes, yo do need more jugs. I recommend buying the 20 L one. Your skills of vet, doctor, and mechanic affect how fast your animals, your people, and your carts/cars heal. These skills are passive. However, if you're seriously hurt, there should be a doctor in most towns that can heal you for about $5/hp point lost.
ultravolt, to get to the store click and drag a portal scroll (they're the purple scrolls) over any of your characters. if you don't have one you can get one from monster drops or treasure chests.
 "Arkandian Explorer"){kind=icon}
 "Arkandian Revenant"){kind=icon}
 "Caravaneer"){kind=icon}
 "Monsters' Den: Book of Dread"){kind=icon}
 "Platform Racing 2"){kind=icon}