My son is 3.5 and gifted. He constantly seeks reassurance as well, and has massive meltdowns when he runs into words he couldn't read the fast way and asked to try sounding out. We've discussed many times how sounding out an unfamiliar word is a valuable skill and there is absolutely no shame in having to use it. But no luck so far.
Frequent wake ups, yes. He's currently in a phase where he is scared of darkness, shadows, carnivorous dinosaurs, wolves, monsters and bears etc. That, and frequent tantrums, I think are both normal for a 3yo, and more so for a gifted 3yo with intense emotions and vivid imaginations.
We had him evaluated at close to 3 by a psychologist and received no diagnosis other than giftedness. But I do believe he has anxiety issues. Bites fingernails and has some motor tics when nervous.