It depends on the distance, like if Sasuke was right next to him also if he surprise attack Naruto like he did a weken Orochimaru. If a couple of feet away then base Naruto can make clones to take the Amaterasu. Also Going into KM does not take time, he can enter the mode in like 1 sec since we seen him automatically go KM. And A dodged Amaterasu while KM shown to dogde A point blank at his fastest speed so KM and BM are dodging it. SM can sense and evade attacks at less at Raikage's speed which is faster than Amaterasu.
Naruto can enter kyuubi mode in a fraction of second, so even if naruto in base mode does get hit with amaterasu he can still enter kyuubi mode to push the flame off in time. It burns way to slow to damage naruto. Karin was minorly burned by it an she was exposed to it for a couple of seconds.
No he can't. KCM is almost instantaneous. Plus, he could make a clone to take the hit so it's plausible that he could somewhat "tank" it in base assuming he knows it's coming.