If you have infinite amount of energy in the past, then you will also have infinite amount of energy in the future. Now if someone could tell me they can harness infinite amount of energy and use that to recreate the future, then maybe I will believe in time travel. But if that happens, I would be using that infinite energy for something else really.
If you drive your car at the speed of light btw, your headlight doesn't go at twice the speed of light. Light is massless, is not affected by atomic forces, doesn't have momentum, and thus isn't pushed forward by massless objects. This is what I said earlier, if you move at the speed of light, and your car doesn't change from atoms to photons ( or into some other massless quantum particles. it will, trust me ), only one same photon can be seen by you at that speed. Thus, your time has stopped. But not the others. And your brain will probably stop working at that time ( the brain utilizes electron which may change based on the EMR properties ).
Moving mass backwards IS creating the past. You cannot create something from nothing, unless you use some magic (even magic needs its ingredients heh ). And something that is infinitely hard IS impossible. lol
If the energy is infinite, how can you conserve it. It's impossible to waste an infinite amount of energy as it never is reduced. That fact is completely relevant.
First comes the solid Law of Conservation: energy cannot be destroyed, energy cannot be created, energy must be conserved.
Second comes a comment from a random person i don't know on the internet: energy is infinite.
Now if energy is infinite, it cannot be conserved ( as you said). But if energy has to be conserved, it cannot be infinite. I choose the first solid law proven many times already. So infinite or not, it's not relevant.

I am happy to answer this again if you don't understand.
Infinite is relative to who you are btw.. A retarded person maybe cannot count more than 3.. so anything more than 3 is infinite to him. It is used to describe an amount which is impossible to occur.