1.) Zarrar is the Tier 1 unit. It was set up on the lines of the British SAS, just like the US Delta Force was/is. Karrar is another unit that was created with American assistance specifically for the WOT. SOTF was yet another unit specifically for FATA ops (specific to the terrain, heli ops, etc.) Karrar has been absorbed into Zarrar now. Zarrar was perfectly capable of handling all roles but was a very small team reserved for HVTs, etc.
2.) An SSG commando can gain skills in various specialties. Courses are run at the Special Operations School and elsewhere (even abroad.) However, some tend to stick to their (very difficult) specializations, like the "frog men" of Musa Coy or the "anti terrorists" of Zarrar. Jack of all trades, master of some
3.) Zarrar, like any Tier 1 unit, is perfectly capable of fighting any enemy force --- however, not in the conventional sense. Read up on JSOC missions --- one can assume that any other worthy Tier 1 unit would have the same mission set, except in our case we are mostly operating internally or in the region (vs. on different continents.)
Actually, the American SMUs are - by all measures - bloody brilliant. Granted, they have the best tech at their disposal and the support of the world's main superpower. But that doesn't mean that tactically they have been very good.
The issue is at the strategic level where the States (in my opinion) wants to get itself into intractable quagmires so it can remain in parts of the world where it wants to maintain a presence.
Also, the phrase "US SF" specifically refers to the US Army Special Forces (aka Green Berets) whose main mission is training guerilla forces in other countries (Foreign Internal Defense, not Direct Action.) Though the US SF does have some direct action-focused teams within it, the premier direct action and special recon units are the SMUs under JSOC (DEVGRU, Delta, ISA, 24th Special Tactics etc.)
Finally, I absolutely agree with your point that our spec ops units (SSG) achieved stunning results against internal militants.
