I like the bull barrel because, well, it looks cool[

]. And it adds some weight, which I like. In my opinion it really isn't needed with a 17 HMR unless you are going to shoot a lot, fast. I don't believe the 17 rimfire generates enough heat to really warant a bigger barrel like that.
I have heard of some of the sporter barrels shooting just as well. But if you are going to get one you might as well get the bull barrel, it can't hurt

. Unless you are going to carry it around a lot, then maybe I would opt for a synthetic stocked sporter barrel. Much lighter to carry, and they have nearly no recoil so that won't matter.
As far as a scope, that depends on your budget, what you want to do with the gun and what you like. My gun is a $200 plain jane savage with a $400 20 power mil dot scope on it. Most expensive scope I own is on the cheapest gun I own

, go figure. After trying several I felt this gun warranted the better scope, it's just that accurate at 100 yards and beyond.
I personally wouldn't waste money on the new scopes that correct for range, like the Sweet 17 and others like it. You just don't need it for this gun. It shoots plenty flat out to the ranges it's effective. Spend the money on better glass in my opinion, you will be glad you did.
I have an Alaskan Guide model from cabela's on mine. It's a 6.5-20x44 with adjustable objective, mil dot reticle and quick detach mounts.
Good luck with what ever you decide on.
Paul