You seem to know what your issue is. What kind of help are you seeking?
Over heating near the camera could be that the flash IC is shorted. Don't quote me on it, but it happens sometimes.
And shorting sometimes leads to battery consumption/drain, unless the battery is plain old, or you have some other issue with the charging and data circuit since you mentioned a broken USB port.
Upgrading will not fix your short/over-heating. You'll have to take it apart and try to figure out which part is overheating, and upload a picture of that component. Then we can help you determine if the component is easily replaceable. Often it's not.
Finally you can have the port repaired. This kind of repair is usually not expensive.
In summary, if you're not prepared to invest a little to have it repaired, there is nothing we can help you with.
If you do want to spend some money on it, you must try to figure out the overheating first, then the broken USB and battery drain second.