Revamping a used scooter

I am thinking of buying the escooter in this picture. It presently has a 48v, 500 watt motor with a 20amp sla battery. I want to replace components on this bike to make it more useful and also to make it safer. If I were to buy a new one, IMHO it would not be any safer than this used one. My questions:
1. Is there a cleaning solution that will remove the oxidation on the light assemblies?
2. The battery and a storage compartment is under the seat. The size of the present battery and the storage compartment is big enough to put a 50 amp Life battery in it without cutting a thing (this is one of the main attractions for this scooter. I can buy a "standard shaped battery" and just drop it into place without other mods. Also, the body looks brand new). I intend to keep the 48v motor for a few months. Do I need to change the controller because of the bigger battery?
3. The scooter will ultimately have a 72v or 96v 1,500 watt motor. That is a significant power change. I can get a new rear fork (or is it called a wish bone?) fabricated for less than US$ 200 heavier gauge steel, etc. Is this necessary to accommodate the increased power, or are there other options?

https://item.jd.com/11007247451.html I am talking to this company now about a battery.

1-yes, you can get headlight polishing kits at any automotive store.
2 -no, you can put as big or little battery as you want as long as the voltage stays the same.
3- if the motor fits, no new fork is needed. The increased torque at the fork would be so negligible. I would get a new fork if you were added a significant amount of weight, but all the force is coming directly from the axel.

Thanks!