A few Virginia class escorts could probably sink almost any non-NATO navy task force on their own. Add a carrier group on top/to the rear of them, and you can scratch "almost".

The Ohio subs do not go unprotected. However, they are designed to be able to carry not only nukes but also cruise missiles (up to 154 Tomahawks for instance), which would make the a huge threat to any naval force.

Also, let's say that these subs were used to deliver a few hundred anti-surface Tomahawks against for instance a Chinese invasion of Taiwan. Not only would the missiles themselves be able to sink a lot of surface assets, the use of these subs would also signal their presence, indicating that the USN was meaning business.

Yes. The primary mission of “fast-attack” submarines are to shoot torpedoes and destroy ships and other submarines.

It takes only one torpedo to disable most surface ships. An American Seawolf class submarine can carry ~50 torpedoes.

Different classes of subs are specialized to do different things. Some specialize as missile platforms, some specialize in hunting other submarines. Many can do both at least to some extent.