C.H.
Based on my experience, this sounds pretty normal for the age. He's getting comfortable hearing himself speak, practicing new vocabulary, and testing reactions and limits. And I'll bet at least once you've laughed or fawned in some way when he first started doing it, because it really was cute then (maybe now not so much!), so he may think of it as an attention grabber.
Although its clearly annoying at times, and you don't want to encourage back talk, it will probably pass. The approach I used (and sometimes still need to--my little guy is 6 now!) was to more or less ignore his back talk focusing on the behavior I was trying to correct, giving him up to three chances to decide to listen to my instruction, depending on the severity of the matter. After that there are escalating consequences, and I always tell him in advance what the consequence will be and that he can make the choice to do as I ask or face the consequence.
Regarding hyperness, remember that at this age they are more in control of their physical being than they have ever been, which is fun and exciting and can give them confidence, yet they still don't have impulse control.
Hang in there! The days, months, years fly by so quickly! Indeed this too shall pass.