some insurance companies are asking if you've had a screen replacement now when you go get a quote,but it shouldnt effect your insurance.
chips near the edge of the screen are harder to fix,simply because there is more stress on that part of the screen,especially if the screen is bonded(glued in)
yer i'd say he was doing you a favour when he said leave it as he would of cracked your screen if he did it mate.
at least you get some more use out of it before paying out money for a new one.
oh some insurance companies are now putting excess on chips,usually £10-£15 pounds!!!!!!