The numbers next to the quests are more there for indicating general progression and to mark the highest level to gain experience from. You get experience from quests as long as you're no more than 5 levels above the level suggestion for them. So the crab quest will grant experience as long as you're level 9 or below. Keep in mind you can have up to 6 people to do the bosses with, so six level 4s would likely have no issues. The low levels are kinda mushed together since you progress through them so quickly, so its kind of hard to give a true difficulty rating to the quests. Things aren't perfect but they're useful as general guidelines IMO.
Also! Do you guys have mercenaries? They can be hired in the tavern in Riversdale. They're not quite as good as an extra player would be, but they do help quite a bit. You can only have one of each (So you can't take 2 healers for example). They count as a "player" in the game, and can only be hired if theres less than 5 players in a game. So since theres 3 of you, two people may take a mercenary as that would be 3 people + 2 mercenaries = 5 players.
Secondarily the new soul system really alleviates some things in the early game as well. As you guys kill monsters; souls should drop and whoever picks them up and uses them will be granted some passive benefits. These are saved to your account rather than character so if you choose to create a new character in the future, whatever souls you found on your first character can be used on your second character. They really help with progressing through the lower areas of the game.
