You don't need a leash with WW unless you're a pretty low summoner level. In fact, most competent junglers don't need a leash on any champion. The only purpose a leash serves is it allows for a quicker first gank. Warwick's early ganks suck unless one of the laners has a good CC.
And yes, while you should be maxing Q first, W gives you more level 1 damage, particularly in combination with Long Sword, which I find to be the best starting item on WW. So your first 6 levels, you should level skills in this order: W, Q, Q, E, Q, R. From that point out, the leveling priority is always either R > Q > W > E, or R > Q > E > W.
Whether you give W or E higher priority kind of depends on how the match is going. Leveling up the E can make it easier for your team to secure kills, and it just gives you a lot of movement speed for chasing or escaping any time an enemy is under half health. If you're the most farmed champion on your team, it's probably better to take the E over W.
But if you're jungling right, there are 3 players on your team more fed than you. Your solotop, solomid, and AD Carry. And in this case, it is better to take the W. The W doesn't end up doing a whole lot for WW, as he can reach the attack speed cap (2.5) without it. And even if you don't push it all the way to the cap, you're still so high that you're not getting the entire W buff because most of it puts you over the speed cap.
BUT, it's an AoE buff. With 5 points in your W, it will double Warwick's attack speed (up to the cap) and give all nearby allies a 50% attack speed buff. This means your AD carry who has 500 AD with 1.5 AS (so he does 750 damage per second) now has 500 AD with 2.25 AS (now he's doing 1,125 damage per second). That's a big damage boost, and that's just on one player. Now imagine when that buff is applied to your whole team as you're standing at dragon, Baron, turret, inhibitor, Nexus, etc.
So, if you're jungling properly and getting your laners fed, the W ends up being a far better way to secure kills for your team, assists for yourself, and objectives.