Is the Companions quest line exclusive with any other?

Solution 1:

You may want to rethink the Werewolf thing.

You can still get cured of Lycanthropy (werewolf-ism) later in the Companions Questline if you really don't want to be a werewolf, but it's really useful.

I've used it to clear out the top-side of forts quickly (where there are 6-7 guards hanging around), and I've used it when I'm facing a really tough boss. It gives you an edge, and if you do the Ill Met By Moonlight Quest and choose to save Sinding, you can keep the Ring without the curse (allowing you an extra transformation every day).

There are two things you miss out on when you're a werewolf: Sleeping bonuses, and Vampirism. But you get neat perks in return (you can get rid of those Cure Disease Potions, and you can get "Wolf Shouts").

Solution 2:

PS: As far as I know the Werewolf form is only exclusive with the Vampire form. If the former is cured, the latter is still excluded reportedly due to a bug. Is that correct?

Correct. Other than that, joining the Companions does not limit anything else in the game. And keep in mind you can only accept the beast blood once. If you cure yourself, you will never gain the ability to become a werewolf again.

Solution 3:

Werewolf doesn't do nothing about the questline. It grants you a power. Only thing is you can't do the power within a city or guards will attack you. You can be cured if you decide to not use the power, but the power is more of an "extra" that doesn't influence the game. You are quite powerfull as werewolf.

Vampirism on the other hand does effect your life in Skyrim so be sure if you wanna follow that path.

Also becoming a werewolf will cure vampirism if you had it. Just so you know.