A pistol grip counts as one feature.
A folding/collapsing stock counts as one feature.
A detachable magazine is not a feature - it's a requirement for the firearm to even be considered under the legislation.
The law does not read "more than two features" - it reads "a semi-auto with the ability to accept a detachable magazine and more than one feature". Heck, I'll post it for you below:
§ 921(a)(30) The term 'semiautomatic assault weapon' means:
...
(B) a semiautomatic rifle that has an ability to accept a detachable magazine and has at least 2 of -
(i) a folding or telescopic stock;
(ii) a pistol grip that protrudes conspicuously beneath the action of the weapon;
(iii) a bayonet mount;
(iv) a flash suppressor or threaded barrel designed to accommodate a flash suppressor; and
(v) a grenade launcher;
View Quote
The key is that without the ability to accept a detachable magazine, a semi-automatic rifle is NOT covered by the AW ban legislation. If you take an AR-15 and weld or otherwise fix the magazine, you can stick a telestock on it, and an upper with flash suppressor and bayonet lug with no legal problems - it cannot be considered a semi-automatic assault weapon.
For the SKS or any other imported rifle, it cannot have 'nonsporting' features if it was imported after the 1990 cutoff date for the Bush 89 nonsporting import ban. That's why SKS's have been coming in neutered. If you put enough US parts in an SKS that it's no longer considered 'imported' under the law, then you can put a folding stock with pistol grip on it, as long as it's got the non-detchable magazine.