98Civic1.4 petrl has overheating problem when idle during hot weather & when a/c is on,suspected oil leak too?

I would start with the simple stuff first. Check your fan relay or fuse and make sure the fan comes on when it gets to normal temp. Next, flush the radiator and make sure theres no excessive rust or blockages. Then, check your oil and look for any "milky" oil. That would mean your headgasket is leaking coolant into the oil. You can also check the thermostat or the temperature sending unit. As for the headgasket, I've never heard of that brand of gaskets, I've always went with Felpro and they've never let me down. Good luck to you.