Q: iPhone charger

i do intend on getting a new one. but I wanted to know if a damaged charger would affect the phone at all. It's really expensive so I don't want to risk it.

the charger works fine just that at the point of insertion the cord is exposed as though it's been bent alot.

its fine if I continue using it till the charger stops working?

So I would have to look for an official iphone store or can i buy it from a vendor down town?

i usually only buy in stores.

But say I some how buy a counterfeit charger, even though i asked for an original charger. Would the phone show signs that the charger is fake, or would the phone instantly start failing and eventually stop working?